arm64: mm: Remove unused support for Device-GRE memory type

The Device-GRE memory type is unused, so remove it and reclaim a MAIR.

Cc: Christoph Hellwig <hch@lst.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210505180228.GA3874@arm.com
Link: https://lore.kernel.org/r/20210527110319.22157-2-will@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

arch/arm64/include/asm/memory.h

@@ -138,7 +138,6 @@
 #define MT_NORMAL_WT		3
 #define MT_DEVICE_nGnRnE	4
 #define MT_DEVICE_nGnRE		5
-#define MT_DEVICE_GRE		6
 
 /*
  * Memory types for Stage-2 translation

arch/arm64/include/asm/sysreg.h

@@ -703,7 +703,6 @@
 /* MAIR_ELx memory attributes (used by Linux) */
 #define MAIR_ATTR_DEVICE_nGnRnE		UL(0x00)
 #define MAIR_ATTR_DEVICE_nGnRE		UL(0x04)
-#define MAIR_ATTR_DEVICE_GRE		UL(0x0c)
 #define MAIR_ATTR_NORMAL_NC		UL(0x44)
 #define MAIR_ATTR_NORMAL_WT		UL(0xbb)
 #define MAIR_ATTR_NORMAL_TAGGED		UL(0xf0)

arch/arm64/mm/proc.S

@@ -58,7 +58,6 @@
 #define MAIR_EL1_SET							\
 	(MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRnE, MT_DEVICE_nGnRnE) |	\
 	 MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRE, MT_DEVICE_nGnRE) |	\
-	 MAIR_ATTRIDX(MAIR_ATTR_DEVICE_GRE, MT_DEVICE_GRE) |		\
 	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL_NC, MT_NORMAL_NC) |		\
 	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL) |			\
 	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL_WT, MT_NORMAL_WT) |		\

arch/arm64/mm/ptdump.c

@@ -157,10 +157,6 @@ static const struct prot_bits pte_bits[] = {
 		.mask	= PTE_ATTRINDX_MASK,
 		.val	= PTE_ATTRINDX(MT_DEVICE_nGnRE),
 		.set	= "DEVICE/nGnRE",
-	}, {
-		.mask	= PTE_ATTRINDX_MASK,
-		.val	= PTE_ATTRINDX(MT_DEVICE_GRE),
-		.set	= "DEVICE/GRE",
 	}, {
 		.mask	= PTE_ATTRINDX_MASK,
 		.val	= PTE_ATTRINDX(MT_NORMAL_NC),