sh: Fix up unaligned current_text_addr().

As noted by Adrian:

	Commit 3ab83521 (kexec jump)
	causes the following build error on sh:

	<--  snip  -->

	...
	  CC      kernel/kexec.o
	{standard input}: Assembler messages:
	{standard input}:1518: Error: offset to unaligned destination
	make[2]: *** [kernel/kexec.o] Error 1

	<--  snip  -->

	If I understand the assembler correctly it fails at
	include/asm-sh/kexec.h:59

The issue here is that the mova reference lacks an explicit alignment,
and previous code paths would end up with this on a 16-bit boundary,
so we make the alignment explicit.

Reported-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>