sparc32: switch to NO_BOOTMEM

Each populated sparc_phys_bank is added to memblock.memory. The
reserve_bootmem() calls are replaced with memblock_reserve(), and the
bootmem bitmap initialization is droppped.

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>