dma-mapping: Fix DMA_BIT_MASK() macro being broken

After commit a50f745 ("dma-mapping: Allow use of DMA_BIT_MASK(64) in
global scope"), the DMA_BIT_MASK() macro is broken when passed non trivial
statements for the value of 'n'. This is caused by the new version missing
parenthesis around 'n' when evaluating 'n'.

One example of this breakage is the IPU6 driver now crashing due to
it getting DMA-addresses with address bit 32 set even though it has
tried to set a 32 bit DMA mask.

The IPU6 CSI2 engine has a DMA mask of either 31 or 32 bits depending
on if it is in secure mode or not and it sets this masks like this:

        mmu_info->aperture_end =
                (dma_addr_t)DMA_BIT_MASK(isp->secure_mode ?
                                         IPU6_MMU_ADDR_BITS :
                                         IPU6_MMU_ADDR_BITS_NON_SECURE);

So the 'n' argument here is "isp->secure_mode ? IPU6_MMU_ADDR_BITS :
IPU6_MMU_ADDR_BITS_NON_SECURE" which gets expanded into:

isp->secure_mode ? IPU6_MMU_ADDR_BITS : IPU6_MMU_ADDR_BITS_NON_SECURE - 1

With the -1 only being applied in the non secure case, causing
the secure mode mask to be one 1 bit too large.

Fixes: a50f745 ("dma-mapping: Allow use of DMA_BIT_MASK(64) in global scope")
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20251207184756.97904-1-johannes.goede@oss.qualcomm.com

Author: Hans de Goede

include/linux/dma-mapping.h

@@ -90,7 +90,7 @@
  */
 #define DMA_MAPPING_ERROR		(~(dma_addr_t)0)
 
-#define DMA_BIT_MASK(n)	GENMASK_ULL(n - 1, 0)
+#define DMA_BIT_MASK(n)	GENMASK_ULL((n) - 1, 0)
 
 struct dma_iova_state {
 	dma_addr_t addr;