iommu: Spelling s/cpmxchg64/cmpxchg64/

Fix misspellings of "cmpxchg64"

Fixes: d286a58b ("iommu: Tidy up io-pgtable dependencies")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/eab156858147249d44463662eb9192202c39ab9f.1678295792.git.geert+renesas@glider.beSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/Kconfig

@@ -33,7 +33,7 @@ config IOMMU_IO_PGTABLE_LPAE
 	bool "ARMv7/v8 Long Descriptor Format"
 	select IOMMU_IO_PGTABLE
 	depends on ARM || ARM64 || COMPILE_TEST
-	depends on !GENERIC_ATOMIC64	# for cpmxchg64()
+	depends on !GENERIC_ATOMIC64	# for cmpxchg64()
 	help
 	  Enable support for the ARM long descriptor pagetable format.
 	  This allocator supports 4K/2M/1G, 16K/32M and 64K/512M page
@@ -72,7 +72,7 @@ config IOMMU_IO_PGTABLE_DART
 	bool "Apple DART Formats"
 	select IOMMU_IO_PGTABLE
 	depends on ARM64 || COMPILE_TEST
-	depends on !GENERIC_ATOMIC64	# for cpmxchg64()
+	depends on !GENERIC_ATOMIC64	# for cmpxchg64()
 	help
 	  Enable support for the Apple DART pagetable formats. These include
 	  the t8020 and t6000/t8110 DART formats used in Apple M1/M2 family