Revert "mm: mmap: fix fput in error path v2"

The kernel test robot is not happy with that.

This reverts commit 0227da01.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/394772/