m68knommu: f_pcr has been gone since headers' merge

sure, it's effectively ifdefed out, but still...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>