Remove suppression for HasSeekPenalty as the underlying problem is fixed

The bug was fixed in
https://crrev.com/8349cde788d93f75c7e82d88c6bc44a43bc19cf5
TBR=glider@chromium.org
BUG=468631

Review URL: https://codereview.chromium.org/1023783003

Cr-Commit-Position: refs/heads/master@{#321467}

tools/valgrind/drmemory/suppressions_full.txt

@@ -1916,13 +1916,6 @@ name=bug_468169
 *!encode_nonrd_sb_row
 *!vp9_encode_tile
 
-UNINITIALIZED READ
-name=bug_468631
-system call NtDeviceIoControlFile InputBuffer
-KERNELBASE.dll!DeviceIoControl
-KERNEL32.dll!DeviceIoControl
-base.dll!base::SysInfo::HasSeekPenalty
-
 UNINITIALIZED READ
 name=bug_468638
 *!egl::ConfigSorter::operator()