tile: parameterize VA and PA space more cleanly

The existing code relied on the hardware definition (<arch/chip.h>)
to specify how much VA and PA space was available.  It's convenient
to allow customizing this for some configurations, so provide symbols
MAX_PA_WIDTH and MAX_VA_WIDTH in <asm/page.h> that can be modified
if desired.

Additionally, move away from the MEM_XX_INTRPT nomenclature to
define the start of various regions within the VA space.  In fact
the cleaner symbol is, for example, MEM_SV_START, to indicate the
start of the area used for supervisor code; the actual address of the
interrupt vectors is not as important, and can be changed if desired.
As part of this change, convert from "intrpt1" nomenclature (which
built in the old privilege-level 1 model) to a simple "intrpt".

Also strip out some tilepro-specific code supporting modifying the
PL the kernel could run at, since we don't actually support using
different PLs in tilepro, only tilegx.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
diff --git a/arch/tile/mm/init.c b/arch/tile/mm/init.c
index 3bfa127..c6d2160 100644
--- a/arch/tile/mm/init.c
+++ b/arch/tile/mm/init.c
@@ -234,7 +234,7 @@
 {
 	int cpu;
 	unsigned long page;
-	enum { CODE_DELTA = MEM_SV_INTRPT - PAGE_OFFSET };
+	enum { CODE_DELTA = MEM_SV_START - PAGE_OFFSET };
 
 #if CHIP_HAS_CBOX_HOME_MAP()
 	/* For kdata=huge, everything is just hash-for-home. */
@@ -538,7 +538,7 @@
 		}
 	}
 
-	address = MEM_SV_INTRPT;
+	address = MEM_SV_START;
 	pmd = get_pmd(pgtables, address);
 	pfn = 0;  /* code starts at PA 0 */
 	if (ktext_small) {
@@ -1021,7 +1021,7 @@
 
 void free_initmem(void)
 {
-	const unsigned long text_delta = MEM_SV_INTRPT - PAGE_OFFSET;
+	const unsigned long text_delta = MEM_SV_START - PAGE_OFFSET;
 
 	/*
 	 * Evict the dirty initdata on the boot cpu, evict the w1data
@@ -1040,7 +1040,7 @@
 
 	/*
 	 * Free the pages mapped from 0xc0000000 that correspond to code
-	 * pages from MEM_SV_INTRPT that we won't use again after init.
+	 * pages from MEM_SV_START that we won't use again after init.
 	 */
 	free_init_pages("unused kernel text",
 			(unsigned long)_sinittext - text_delta,