slub: Fix gcc warning

Second hortest commit of history. Source:
https://github.com/LegacyXperia/android_kernel_semc_msm7x30/commit/6ecdb
b9168a2c79aea2d07468106715136aa7848
crypto: msm: check potential integer overflow

Too dumb for Git. Copied manually from CAF’s commit,
Ie7708000bfd8c57e2fba8e02230a7ce9cdc9634c.
qseecom: fix secure app loading failure by ...

…kernel mode qseecom client
Another CAF edit. I1ac39ee885c12e08e863d976321dda2380ace852.