atmel_serial: remove duplicated macro definition

After commit 39d4c922

 (atmel_serial: fix
uart/console concurrent access) the UART_GET_TCR macro got redefined. This
patch removes the duplicated definition.

Signed-off-by: michael trimarchi <trimarchimichael@evidence.eu.com>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>