soundwire: clarify maximum allowed address

The existing code sets the maximum address at 0x80000000, which is not
completely accurate. The last 2 Gbytes are indeed reserved, but so are
the 896 Mbytes just before. The maximum address which can be used with
paging or BRA is 0x47FFFFFF per Table 131 of the SoundWire 1.2.1
specification.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20240326090122.1051806-6-yung-chuan.liao@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

include/linux/soundwire/sdw_registers.h

@@ -13,7 +13,7 @@
 
 #define SDW_REG_NO_PAGE				0x00008000
 #define SDW_REG_OPTIONAL_PAGE			0x00010000
-#define SDW_REG_MAX				0x80000000
+#define SDW_REG_MAX				0x48000000
 
 #define SDW_DPN_SIZE				0x100
 #define SDW_BANK1_OFFSET			0x10