kernel: proc: use the same treatment to check proc_lseek as ones for proc_read_iter et.al

In the Linux kernel, the following vulnerability has been resolved: proc: use the same treatment to check proclseek as ones for procreaditer et.al Check pde-procops-proclseek directly may cause UAF in rmmod scenario. It's a gap in procregopen after commit 654b33ada4ab"proc: fix UAF in...