spi: img-spfi: fix kbuild test robot warning

drivers/spi/spi-img-spfi.c: In function 'img_spfi_setup':
drivers/spi/spi-img-spfi.c:446: warning: 'ret' may be used
uninitialized in this function.

Fixes: commit b03ba9e3

 ("spi: img-spfi: fix multiple calls to request gpio")
Signed-off-by: Sifan Naeem <sifan.naeem@imgtec.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org