include/linux/pgtable.h: : remove redundant pte variable

Return value from ptep_get_and_clear_full() directly instead of taking
this in another redundant variable.

Link: https://lkml.kernel.org/r/202211282107437343474@zte.com.cn


Signed-off-by: zhang songyi <zhang.songyi@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>