mm/memblock.c: cast constant ULLONG_MAX to phys_addr_t

This fixes a warning shown when phys_addr_t is 32-bit int when compiling
with clang:

  mm/memblock.c:927:15: warning: implicit conversion from 'unsigned long long'
        to 'phys_addr_t' (aka 'unsigned int') changes value from
        18446744073709551615 to 4294967295 [-Wconstant-conversion]
                                  r->base : ULLONG_MAX;
                                            ^~~~~~~~~~
  ./include/linux/kernel.h:30:21: note: expanded from macro 'ULLONG_MAX'
  #define ULLONG_MAX      (~0ULL)
                           ^~~~~

Link: http://lkml.kernel.org/r/20180319005645.29051-1-stefan@agner.ch
Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memblock.c

@@ -925,7 +925,7 @@ void __init_memblock __next_mem_range(u64 *idx, int nid, ulong flags,
 			r = &type_b->regions[idx_b];
 			r_start = idx_b ? r[-1].base + r[-1].size : 0;
 			r_end = idx_b < type_b->cnt ?
-				r->base : ULLONG_MAX;
+				r->base : (phys_addr_t)ULLONG_MAX;
 
 			/*
 			 * if idx_b advanced past idx_a,
@@ -1041,7 +1041,7 @@ void __init_memblock __next_mem_range_rev(u64 *idx, int nid, ulong flags,
 			r = &type_b->regions[idx_b];
 			r_start = idx_b ? r[-1].base + r[-1].size : 0;
 			r_end = idx_b < type_b->cnt ?
-				r->base : ULLONG_MAX;
+				r->base : (phys_addr_t)ULLONG_MAX;
 			/*
 			 * if idx_b advanced past idx_a,
 			 * break out to advance idx_a