tty/serial: at91: correct buffer size used in DMA
tty/serial: at91: correct buffer size used in DMA

The buffer size set in DMA is inconsistent with its allocation.
So keep them consistent here. The structure atmel_uart_char is
used in PIO mode with its meaning. But here in DMA, all of the
buffer is treated as general char.

Signed-off-by: Leilei Zhao <04f208ce523fe5710e61baa85f06d3b331ae3249@atmel.com>
Acked-by: Nicolas Ferre <45b517be0e5ec6dc3a39715767c1d18e090d39b4@atmel.com>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs