mtd: move more manufacturers to the common cfi.h header file

Move MANUFACTURER_MACRONIX and MANUFACTURER_SST definitions to the
include/linux/mtd/cfi.h header file and rename them to CFI_MFR_MACRONIX and
CFI_MFR_SST.

All references in drivers/mtd/chips/cfi_cmdset_0002.c are updated to reflect
this.

Signed-off-by: Guillaume LECERF <glecerf@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>