powerpc/kaslr_booke: Fix build error

powerpc/kaslr_booke: Fix build error

arch/powerpc/mm/nohash/kaslr_booke.c: In function ‘kaslr_get_cmdline’:
arch/powerpc/mm/nohash/kaslr_booke.c:46:2: error: implicit declaration of function ‘early_init_dt_scan_chosen’
  early_init_dt_scan_chosen(boot_command_line);
  ^~~~~~~~~~~~~~~~~~~~~~~~~

arch/powerpc/mm/nohash/kaslr_booke.c: In function ‘get_initrd_range’:
arch/powerpc/mm/nohash/kaslr_booke.c:210:10: error: implicit declaration of function ‘of_read_number’
  start = of_read_number(prop, len / 4);
          ^~~~~~~~~~~~~~

Add missing include files to fix this.

Fixes: 86c38fec69a4 ("powerpc: Remove asm/prom.h from all files that don't need it")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220517094900.14900-1-yuehaibing@huawei.com