x86: Remove unnecessary casts of void ptr returning alloc function return values

The [vk][cmz]alloc(_node) family of functions return void
pointers which it's completely unnecessary/pointless to cast to
other pointer types since that happens implicitly.

This patch removes such casts from arch/x86.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Cc: trivial@kernel.org
Cc: amd64-microcode@amd64.org
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
LKML-Reference: <alpine.LNX.2.00.1011082310220.23697@swampdragon.chaosbits.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>