ARM: mach-shmobile: pfc-sh73a0: fixup MSEL2CR MSEL18 for I2C-3

MSEL2CR MSEL18 should be 1 if I2C-3

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Simon Horman <horms@verge.net.au>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>