[DRIVERS] 8250-uart: Check and handle all possible Rx related error conditions upon Rx interrupt

The method of handling all Rx related errors (i.e. framing, parity, overflow, and break errors) is the same.

To get out a Rx error condition we have keep reading the Rx FIFO till the Rx error condition is cleared.

Signed-off-by: Anup Patel <anup@brainfault.org>