arm64: mm: Drop 'const' from conditional arm64_dma_phys_limit definition

commit 7700934 upstream.

Commit 0314956 ("arm64: Do not defer reserve_crashkernel() for
platforms with no DMA memory zones") introduced different definitions
for 'arm64_dma_phys_limit' depending on CONFIG_ZONE_DMA{,32} based on
a late suggestion from Pasha. Sadly, this results in a build error when
passing W=1:

  | arch/arm64/mm/init.c:90:19: error: conflicting type qualifiers for 'arm64_dma_phys_limit'

Drop the 'const' for now and use '__ro_after_init' consistently.

Link: https://lore.kernel.org/r/202203090241.aj7paWeX-lkp@intel.com
Link: https://lore.kernel.org/r/CA+CK2bDbbx=8R=UthkMesWOST8eJMtOGJdfMRTFSwVmo0Vn0EA@mail.gmail.com
Fixes: 0314956 ("arm64: Do not defer reserve_crashkernel() for platforms with no DMA memory zones")
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm64/mm/init.c

@@ -87,7 +87,7 @@ EXPORT_SYMBOL(memstart_addr);
 #if IS_ENABLED(CONFIG_ZONE_DMA) || IS_ENABLED(CONFIG_ZONE_DMA32)
 phys_addr_t __ro_after_init arm64_dma_phys_limit;
 #else
-const phys_addr_t arm64_dma_phys_limit = PHYS_MASK + 1;
+phys_addr_t __ro_after_init arm64_dma_phys_limit = PHYS_MASK + 1;
 #endif
 
 #ifdef CONFIG_KEXEC_CORE