ARM: 9097/1: mmu: Declare section start/end correctly

The kernel test robot reported an interesting bug:

A debug print was using %08x with kernel_sec_start and kernel_sec_end
being phys_addr_t which can be either u32 or u64 (possibly more).

Actually these should just be declared as u32 to begin with: they are
declared as such in the assembly in head.S and the kernel definitely
boots in a 32 bit physical address space. Redeclare the kernel_sec_start
and kernel_sec_end to rid the bug.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: 6e121df1

 ("ARM: 9090/1: Map the lowmem and kernel separately")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>