WATCHDOG: use base address from platform resources and make 2430 boot again

Modfied watchdog driver to use base address provided in platform defn
Cleaned up a bunch of statics used.
Added 2430 baseaddress defn
Addressed review comments for patch1 and 2 reported by Trilok Soni and Tony

Signed-off-by: Nishanth Menon <menon.nishanth@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>