drivers/gfx/generic: Use 'noop_read_resources'

The generic device attached to this driver doesn't have resources
separate from the parent device to which it's attached, so
use 'noop_read_resources' to suppress a false-positive error in
the cbmem console log (GENERIC: 0.0 missing read_resources).

Change-Id: I985318dcc7cc32aaa3f6a599ade95e065900031e
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/88012
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Sean Rhodes <sean@starlabs.systems>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/drivers/gfx/generic/generic.c

@@ -189,6 +189,7 @@ static const char *gfx_acpi_name(const struct device *dev)
 static struct device_operations gfx_ops = {
 	.acpi_name	= gfx_acpi_name,
 	.acpi_fill_ssdt	= gfx_fill_ssdt_generator,
+	.read_resources = noop_read_resources
 };
 
 static void gfx_enable(struct device *dev)