ARCv2: MMUv4: cache programming model changes

Caveats about cache flush on ARCv2 based cores

- dcache is PIPT so paddr is sufficient for cache maintenance ops (no
  need to setup PTAG reg

- icache is still VIPT but only aliasing configs need PTAG setup

So basically this is departure from MMU-v3 which always need vaddr in
line ops registers (DC_IVDL, DC_FLDL, IC_IVIL) but paddr in DC_PTAG,
IC_PTAG respectively.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/cache.h

@@ -82,4 +82,7 @@ extern void read_decode_cache_bcr(void);
 #define DC_CTRL_INV_MODE_FLUSH  0x40
 #define DC_CTRL_FLUSH_STATUS    0x100
 
+/*System-level cache (L2 cache) related Auxiliary registers */
+#define ARC_REG_SLC_CFG		0x901
+
 #endif /* _ASM_CACHE_H */