tty: xuartps: Don't write IRQ disable register to enable interrupts

A comment states, that, according to the data sheet, to enable
interrupts the disable register should be written, but the enable
register could be left untouched. And it suspsects a HW bug requiring
to write both.
Reviewing the data sheet, these statements seem wrong. Just as one would
expect. Writing to the enable/disable register enables/disables
interrupts.
Hence the misleading comment and needless write to the disable register
are removed from the enable sequence.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Tested-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/xilinx_uartps.c

@@ -1085,11 +1085,7 @@ static void xuartps_console_write(struct console *co, const char *s,
 
 	xuartps_writel(ctrl, XUARTPS_CR_OFFSET);
 
-	/* restore interrupt state, it seems like there may be a h/w bug
-	 * in that the interrupt enable register should not need to be
-	 * written based on the data sheet
-	 */
-	xuartps_writel(~imr, XUARTPS_IDR_OFFSET);
+	/* restore interrupt state */
 	xuartps_writel(imr, XUARTPS_IER_OFFSET);
 
 	if (locked)