staging, unisys: remove leftover function kmalloc_kernel()

kmalloc_kernel() previously declared in timskmodutils.h which recently got
removed. Now also remove kmalloc_kernel(), because it's not used anywhere.

Signed-off-by: WANG Chao <wangchao19890207@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>