arm64: mm: avoid name clash in __page_to_voff()

The arm64 __page_to_voff() macro takes a parameter called 'page', and
also refers to 'struct page'. Thus, if the value passed in is not
called 'page', we'll refer to the wrong struct name (which might not
exist).

Fixes: 3fa72fe9c614 ("arm64: mm: fix __page_to_voff definition")
Acked-by: Mark Rutland <mark.rutland@arm.com>
Suggested-by: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Signed-off-by: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@epam.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>