Replace offset handling code with a single call
to memory_read_from_buffer() to simplify read_bmof().

Tested on a ASUS PRIME B650-PLUS.
Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
Tested-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20230730204550.3402-2-W_Armin@gmx.deReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>