mtd: cfi_cmdset_0002: remove redundant assignment to variable ret

Variable ret is being assigned a value that is never read, the following
goto statement jumps to a statement that assigns ret a return from the
call to function do_write_oneword_once. The assignment is redundant
and can be removed.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20241002172258.958113-1-colin.i.king@gmail.com