Remove write to /sys/fs/selinux/checkreqprot

This SELinux option has been deprecated in the kernel since v5.7. In
v6.4, commit a7e4676e made any write to this file a no-op.

Since v4.4, the default value of 0 is set by the kernel. Skip the
setting of this value since we only support kernel >= 4.14.

Test: presubmit
Change-Id: Ied5945532e10b156dc0d9996b2a41a99d04e750b