zram: reshuffle zram_free_page() flags operations

Drop some redundant zram_test_flag() calls and re-order zram_clear_flag()
calls.  Plus two small trivial coding style fixes.  No functional changes.

Link: https://lkml.kernel.org/r/20240917021020.883356-7-senozhatsky@chromium.org


Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>