drivers: ti: uart: remove UART_FCR writes

This patch removes the code that touched UART_FCR, from
console_core_putc(). The check for whether transmit FIFO is
full is sufficient before writing to UART TX FIFO. In fact
setting UARTFCR_TXCLR immediately after a byte is written to
FIFO might even result in loss of that byte, if UART hasn't
sent that byte out yet.

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>