cfi_flash: do not reset flash when probe fails

The CFI flash driver starts at flash_init() which calls down into
flash_get_size().  This starts by calling flash_detect_cfi().  If said
function fails, flash_get_size() finishes by attempting to reset the
flash.  Unfortunately, it does this with an info->portwidth set to 0x10
which filters down into flash_make_cmd() and that happily smashes the
stack by sticking info->portwidth bytes into a cfiword_t variable that
lives on the stack.  On a 64bit system you probably won't notice, but
killing the last 8 bytes on a 32bit system usually leads to a corrupt
return address.  Which is what happens on a Blackfin system.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Stefan Roese <sr@denx.de>