As nommu architecture uses __va definition in asm-generic, it is casted
with (void*) after the macro. But pfn_to_virt definition is using shift
operation after the cast so, compilers raise warnings/errors/
I suppose this is an upstream bug when they introduce the commit.
Fixes: 2d78057f0d ("asm-generic/page.h: Make pfn accessors static inlines")
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>