POWERPC: Change fallocate to match unistd.h on powerpc

POWERPC: Change fallocate to match unistd.h on powerpc

patch f2205fbb5a8933514fd343cc329df631802b4543 in mainline.

Fix the fallocate system call on powerpc to match its unistd.h.

This implies none of these system calls are currently working with the
unistd.h sys call values:
	fallocate
	signalfd
	timerfd
	eventfd
	sync_file_range2

Signed-off-by: Patrick Mansfield <patmans@us.ibm.com>
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>