ANDROID: mm: fix mixed declaration and code warning

This fixes the following warning:
mm/memory.c: In function ‘___handle_speculative_fault’:
mm/memory.c:4871:2: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
 4871 |  struct mempolicy *pol;
      |  ^~~~~~

Bug: 183339614
Fixes: 1c537174 (FROMLIST: mm: provide speculative fault infrastructure)
Reported-by: kernelci.org bot <bot@kernelci.org>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Change-Id: Iebb8c7b4f7c01688bfbb9770653063015ae47020