MIPS: uasm: Add option to export uasm API.

MIPS: uasm: Add option to export uasm API.

A 'select EXPORT_UASM' in Kconfig will cause the uasm to be exported
for use in modules.  When it is exported, all the uasm data and code
cease to be __init and __initdata.

Also daddiu_bug cannot be __cpuinitdata if uasm is exported.  The
cleanest thing is to just make it normal data.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
To: wim@iguana.be
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/1500/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>