media: v4l2-fwnode: simplify v4l2_fwnode_reference_parse_int_props()

The logic at v4l2_fwnode_reference_parse_int_props() is somewhat
complex and violates Linux coding style, as it does multiple
statements on a single line. That makes static analyzers to
be confused, as warned by smatch:

	drivers/media/v4l2-core/v4l2-fwnode.c:832 v4l2_fwnode_reference_parse_int_props() warn: passing zero to 'PTR_ERR'

Simplify the logic, in order to make clearer about what happens
when v4l2_fwnode_reference_get_int_prop() returns an error.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>