ARM/dma-mapping: const a pointer to bus_type in arm_iommu_create_mapping()

Change the function arm_iommu_create_mapping() to take a pointer to a
const bus_type as the function does not modify the variable the pointer
points to at all, and the driver core bus functions it calls all expect
a const * type.

Cc: Russell King <linux@armlinux.org.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20230313182918.1312597-33-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm/include/asm/dma-iommu.h

@@ -24,7 +24,7 @@ struct dma_iommu_mapping {
 };
 
 struct dma_iommu_mapping *
-arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, u64 size);
+arm_iommu_create_mapping(const struct bus_type *bus, dma_addr_t base, u64 size);
 
 void arm_iommu_release_mapping(struct dma_iommu_mapping *mapping);
 

arch/arm/mm/dma-mapping.c

@@ -1543,7 +1543,7 @@ static const struct dma_map_ops iommu_ops = {
  * arm_iommu_attach_device function.
  */
 struct dma_iommu_mapping *
-arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, u64 size)
+arm_iommu_create_mapping(const struct bus_type *bus, dma_addr_t base, u64 size)
 {
 	unsigned int bits = size >> PAGE_SHIFT;
 	unsigned int bitmap_size = BITS_TO_LONGS(bits) * sizeof(long);