drivers/tty/hvc/hvc_tile.c: properly return -EAGAIN

We were returning zero if no bytes could be written to the Tilera
hypervisor console device, but this causes the output to be truncated.
By returning -EAGAIN the tty hvc driver will come back and try again,
which gives the semantics we want, and avoids dropping console output.

Acked-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Chris Metcalf <[e-mail]>

drivers/tty/hvc/hvc_tile.c

···
 			      _SIM_CONTROL_OPERATOR_BITS));
 		return 0;
 	} else {
-		return hv_console_write((HV_VirtAddr)buf, count);
+		/* Translate 0 bytes written to EAGAIN for hvc_console_print. */
+		return hv_console_write((HV_VirtAddr)buf, count) ?: -EAGAIN;
 	}
 }