perf/ring_buffer: Modify the parameter type of perf_mmap_free_page()

In perf_mmap_free_page(), the unsigned long type is converted to the
pointer type, but where the call is made, the pointer type is converted
to the unsigned long type. There is no need to do these operations.

Modify the parameter type of perf_mmap_free_page() to pointer type.

Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <jolsa@redhat.co>
Cc: <acme@kernel.org>
Cc: <mingo@redhat.com>
Cc: <mark.rutland@arm.com>
Cc: <namhyung@kernel.org>
Cc: <alexander.shishkin@linux.intel.com>
Link: https://lkml.kernel.org/r/e6ae3f0c-d04c-50f9-544a-aee3b30330cd@huawei.com