MIPS: VDSO: Avoid use of linux/irqchip/mips-gic.h

Our VDSO code makes use of macros from linux/irqchip/mips-gic.h to
provide offsets to register values, but these are trivial offsets to the
two 32 bit halves of a 64 bit value. Replace use of the macros with zero
(ie. omit adding an offset) and the size of the low 32 bit of the value.
This removes our need for linux/irqchip/mips-gic.h & prepares us for it
to be removed.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17047/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>