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.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>