MIPS: CM: Rename mips_cm_base to mips_gcr_base

MIPS: CM: Rename mips_cm_base to mips_gcr_base

We currently have a mips_cm_base variable which holds the base address
of the Coherence Manager (CM) Global Configuration Registers (GCRs), and
accessor functions which use the GCR in their names. This works fine,
but gets in the way of sharing the code to generate the accessor
functions with other blocks (ie. CPC & GIC) because that code would then
need to separately handle the name of the base address variable & the
name used in the accessor functions.

In order to prepare for sharing the accessor generation code between CM,
CPC & GIC code this patch renames mips_cm_base to mips_gcr_base such
that the "gcr" portion is common to both the base address variable & the
accessor function names.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16999/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>