scsi: ufs: move power definitions to unipro header file

As rate, and mode reside in unipro.h file, also gear enumerations should
be there. especially as those enums can be accessed from other source
files in ufs domain.

Change-Id: Icf6477417cdcab785f94b8095f1024bf24dc983c
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>