Change lmb to use phys_size_t/phys_addr_t

This updates the lmb code to use phys_size_t
and phys_addr_t instead of unsigned long.  Other code
which interacts with this code, like getenv_bootm_size()
is also updated.

Booted on MPC8641HPCN, build-tested ppc, arm, mips.

Signed-off-by: Becky Bruce <becky.bruce@freescale.com>