altera_uart: Simplify altera_uart_console_putc

The check for the TRDY flag after writing the character is not needed.
Also do a cpu_relax() inside the loop.

Pass a struct uart_port to altera_uart_console_putc, so we do not need
to get it (and dereference pointers) for every character.

Cc: Thomas Chou <thomas@wytron.com.tw>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>