i2c: npcm7xx: Remove redundant ret variable

Return value from npcm_i2c_get_slave_addr() directly instead of taking
this in another redundant variable.

This improvement has been suggested by Zeal Robot <zealci@zte.com.cn>

Signed-off-by: Zhang Songyi <zhang.songyi@zte.com.cn>
Link: https://lore.kernel.org/r/20250320004321.1914366-1-andi.shyti@kernel.org


Signed-off-by: Andi Shyti <andi.shyti@kernel.org>