pflash_cfi01: Suppress warning when Linux probes for AMD flash

pflash_cfi01: Suppress warning when Linux probes for AMD flash

There are several ARM and MIPS boards which are manufactured with
either Intel (pflash_cfi01.c) or AMD (pflash_cfi02.c) flash memory.

The Linux kernel supports both and first probes for AMD flash which
resulted in one or two warnings from the Intel flash emulation:

pflash_write: Unimplemented flash cmd sequence (offset 0000000000000000, wcycle 0x0 cmd 0x0 value 0xf000f0)
pflash_write: Unimplemented flash cmd sequence (offset 0000000000000000, wcycle 0x0 cmd 0x0 value 0xf0)

These warnings confuse users, so suppress them.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>