firmware: ti_sci: Fix gcc unused-but-set-variable warning

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/firmware/ti_sci.c: In function ti_sci_cmd_ring_config:
drivers/firmware/ti_sci.c:2035:17: warning: variable dev set but not used [-Wunused-but-set-variable]
drivers/firmware/ti_sci.c: In function ti_sci_cmd_ring_get_config:
drivers/firmware/ti_sci.c:2104:17: warning: variable dev set but not used [-Wunused-but-set-variable]
drivers/firmware/ti_sci.c: In function ti_sci_cmd_rm_udmap_tx_ch_cfg:
drivers/firmware/ti_sci.c:2287:17: warning: variable dev set but not used [-Wunused-but-set-variable]
drivers/firmware/ti_sci.c: In function ti_sci_cmd_rm_udmap_rx_ch_cfg:
drivers/firmware/ti_sci.c:2357:17: warning: variable dev set but not used [-Wunused-but-set-variable]

Use the 'dev' variable instead of info->dev to fix this.

Acked-by: Suman Anna <s-anna@ti.com>
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>