mailbox: remove unneeded 'fast_io' parameter in regmap_config

When using MMIO with regmap, fast_io is implied. No need to set it
again.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>

Author: Wolfram Sang

drivers/mailbox/qcom-apcs-ipc-mailbox.c

@@ -58,7 +58,6 @@ static const struct regmap_config apcs_regmap_config = {
 	.reg_stride = 4,
 	.val_bits = 32,
 	.max_register = 0x1008,
-	.fast_io = true,
 };
 
 static int qcom_apcs_ipc_send_data(struct mbox_chan *chan, void *data)