serial: ifx6x60: del_timer_sync must not be called in interrupt context.

This patch make use of del_timer instead of del_timer_sync in the
interrupt context.
The spi_timer function don't use any resources that may release after
running del_timer,
so using the del_timer is also safe and enough in this context.

Signed-off-by: Chen Jun <jun.d.chen@intel.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Tested-by: Chuansheng Liu <chuansheng.liu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/ifx6x60.c

@@ -866,7 +866,7 @@ error_ret:
 static void ifx_spi_handle_srdy(struct ifx_spi_device *ifx_dev)
 {
 	if (test_bit(IFX_SPI_STATE_TIMER_PENDING, &ifx_dev->flags)) {
-		del_timer_sync(&ifx_dev->spi_timer);
+		del_timer(&ifx_dev->spi_timer);
 		clear_bit(IFX_SPI_STATE_TIMER_PENDING, &ifx_dev->flags);
 	}