linux-user: correct timerfd_create syscall numbers

x86, m68k, ppc, sh4 and sparc failed to enable timerfd, because they
didn't have timerfd_create system call defined. Instead QEMU
defined timerfd syscall. Checking with kernel sources, it appears
kernel developers reused timerfd syscall number with timerfd_create,
presumably since no userspace called the old syscall number.

Reported-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
