fbdev/core: Fix style of code for boot-up logo

Fix a number of warnings from checkpatch.pl in this code before
moving it into a separate file. This includes

 * Prefer 'unsigned int' to bare use of 'unsigned'
 * space required after that ',' (ctx:VxV)
 * space prohibited after that open parenthesis '('
 * suspect code indent for conditional statements (16, 32)
 * braces {} are not necessary for single statement blocks

No functional changes.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230907085408.9354-4-tzimmermann@suse.de