m68k/atari: Rename "scc" to "atari_scc"

It's a way too generic name for a global #define and conflicts with a variable
with the same name, causing build errors like:

| drivers/staging/brcm80211/brcmfmac/../util/siutils.c: In function ‘_si_clkctl_cc’:
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1364: error: expected identifier or ‘(’ before ‘volatile’
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1364: error: expected ‘)’ before ‘(’ token
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1421: error: incompatible types in assignment
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1422: error: invalid operands to binary &
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1423: error: invalid operands to binary &
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1424: error: invalid operands to binary |
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: aggregate value used where an integer was expected
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: aggregate value used where an integer was expected
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: aggregate value used where an integer was expected
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: aggregate value used where an integer was expected
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: aggregate value used where an integer was expected
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: aggregate value used where an integer was expected
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: aggregate value used where an integer was expected
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: aggregate value used where an integer was expected
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: aggregate value used where an integer was expected
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: aggregate value used where an integer was expected
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: aggregate value used where an integer was expected
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1425: error: incompatible type for argument 4 of ‘bcmsdh_reg_write’
| drivers/staging/brcm80211/brcmfmac/../util/siutils.c:1428: error: invalid operands to binary &
| make[8]: *** [drivers/staging/brcm80211/brcmfmac/../util/siutils.o] Error 1

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>