drm/format: Use appropriate types in expect/assert

drm_format_info_* functions don't return bool, and the info variable is a
pointer.
Expecting non-NULL info will cause the test to crash if it is NULL in
checks that follow (which dereference it).
Use appropriate KUNIT_EXPECT/KUNIT_ASSERT variants.

Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Reviewed-by: Maíra Canal <mairacanal@riseup.net>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20220831215608.349269-1-michal.winiarski@intel.com