rtlwifi: rtl8192ce: Refactor rtl8192ce/dm

To reuse as much code as possible when adding additional drivers to the
rtlwifi tree, the common parts of various routines are moved to
drivers/net/wireless/rtlwifi. This patch does that for the version of
dm.{h,c} used by rtl8192ce.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>