xtensa: fix build warning

This fixes the following build warnings:

arch/xtensa/mm/misc.S: Assembler messages:
arch/xtensa/mm/misc.S:143: Warning: value 0xffffffff30000106 truncated to 0x30000106
arch/xtensa/mm/misc.S:197: Warning: value 0xffffffff30000106 truncated to 0x30000106

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
WIP: xtensa: SMP clockevent

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
WIP: xtensa: keep a3 and excsave1 on entry to exception handlers

Based on the SMP patch by Joe Taylor and subsequent fixes.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
WIP: xtensa: add SMP support

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>