media: atomisp: do not free kmalloc memory by vfree

fw_minibuffer[i].buffer is allocated by kmalloc in sh_css_load_blob_info
and by vmalloc in setup_binary. So use kvfree to decide which of those
allocators to use for freeing.

Also remove the useless cast.

Link: https://lore.kernel.org/linux-media/20210219101216.28406-1-jslaby@suse.cz


Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>