framebuffer: Add fb_<level> convenience logging macros

Add fb_<level> convenience macros for emitting the
"fb%d: ", struct fb_info->node value.

Neatens and shortens the code a bit.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>