spl: spl_nor: Remove unused variable 'ret' warning

spl: spl_nor: Remove unused variable 'ret' warning

With the if statement now for the legacy image handling, the compiler
now generates this compile time warning:

common/spl/spl_nor.c:27:6: warning: unused variable 'ret' [-Wunused-variable]

This patch removes this warning by changing the 'ret' variable handling.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Cc: Weijie Gao <weijie.gao@mediatek.com>
Cc: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>