pinctrl: Return -ENOSYS when system call is not available

Update the code to use -ENOSYS, which is the correct error code for an
unimplemented system call in U-Boot.

Also we should not check for a missing operations array as this is not
permitted. For now this can be covered by an assert().

Signed-off-by: Simon Glass <sjg@chromium.org>
1 file changed