arm nomadik: use 1000 as HZ value and rewrite timer code

This sets CONFIG_SYS_HZ to 1000 as required, and completely rewrites
timer code, which is now both correct and much smaller.  Unused
functions like udelay_masked() have been removed as no driver uses
them, even the ones that are not currently active for this board.
mtu.h is copied literally from the kernel sources.

Signed-off-by: Alessandro Rubini <rubini@unipv.it>
Acked-by: Andrea Gallo <andrea.gallo@stericsson.com>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>