Use uart_console() helper in instead of open coded variant.

Note, SERIAL_CORE_CONSOLE is selected by SERIAL_PIC32_CONSOLE,
thus no functional changes expected.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200311090027.64441-1-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>