ARM: 8826/1: mm: initialize pfn limits with find_limits()

The max_low_pfn value must be set before sparse_init() is called to
keep the early memblock allocations and frees balanced for kmemleak
initialization when sparsemem is enabled.

This commit accomplishes that by replacing the local variables min,
max_low, and max_high with the global limit variables min_low_pfn,
max_low_pfn, and max_pfn respectively in bootmem_init(). The global
variables are initialized directly by find_limits() and used in the
remainder of the function.

Fixes: 9099daed ("mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping")
Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>