Remove references to kernel macros.

The macros __force, __bitwise, __user are related to a kernel tool called
sparse to find kernel bugs. These macros are always defined as nothing
in the current uapi kernel header files, so these don't need to be here.

Change-Id: I37ab48123a85b3f9b8f67920e9d56cf518b32597
Test: Builds without warningers/errors.