media: ov2740: Use traditional pattern when checking error codes

Instead of 'if (!ret)' switch to "check for the error first" rule.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>