media: atomisp: Deduplicate return ret in gmin_i2c_write()

Deduplicate return ret in gmin_i2c_write().

While here, replace 'Kernel' by 'kernel' in the message and
reduce amount of LOCs.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>