x86/msr: Add compatibility wrappers for rdmsrl()/wrmsrl()

To reduce the impact of the API renames in -next, add compatibility
wrappers for the two most popular MSR access APIs: rdmsrl() and wrmsrl().

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Xin Li <xin@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org