firmware: arm_scmi: use ioread64() instead of ioread64_hi_lo()

The scmi_common_fastchannel_db_ring() function calls either ioread64()
or ioread64_hi_lo() depending on whether it is compiler for 32-bit
or 64-bit architectures.

The same logic is used to define ioread64() itself in the
linux/io-64-nonatomic-hi-lo.h header file, so the special case
is not really needed.

The behavior here should not change at all.

Fixes: 6f9ea4d ("firmware: arm_scmi: Generalize the fast channel support")
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20250304144346.1025658-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Author: arndb

drivers/firmware/arm_scmi/driver.c

@@ -1997,17 +1997,7 @@ static void scmi_common_fastchannel_db_ring(struct scmi_fc_db_info *db)
 	else if (db->width == 4)
 		SCMI_PROTO_FC_RING_DB(32);
 	else /* db->width == 8 */
-#ifdef CONFIG_64BIT
 		SCMI_PROTO_FC_RING_DB(64);
-#else
-	{
-		u64 val = 0;
-
-		if (db->mask)
-			val = ioread64_hi_lo(db->addr) & db->mask;
-		iowrite64_hi_lo(db->set | val, db->addr);
-	}
-#endif
 }
 
 /**