kfence: fix typo in test

kfence: fix typo in test

Fix a typo/accidental copy-paste that resulted in the obviously
incorrect 'GFP_KERNEL * 2' expression.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Alexander Potapenko <glider@google.com>
[port kfence feature to rpi-5.10.95]
Signed-off-by: Sung-hun Kim <sfoon.kim@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: I157e9378f99fe2b1db005ee402dc0cdb6fe54164