From: Arnd Bergmann <arnd@xxxxxxxx>
The fb_io_mmap() function is used in the file operations but
not enabled in all configurations unless FB_IOMEM_FOPS gets
selected:
ld.lld-20: error: undefined symbol: fb_io_mmap
referenced by wm8505fb.c
drivers/video/fbdev/wm8505fb.o:(wm8505fb_ops) in archive vmlinux.a
Fixes: 11754a504608 ("fbdev/wm8505fb: Initialize fb_ops to fbdev I/O-memory helpers")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>