media: max2175: fix max2175_set_csm_mode() error code

This is supposed to return negative error codes but the type is bool so
it returns true instead.

Fixes: b47b79d8 ("[media] media: i2c: max2175: Add MAX2175 support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>