char: dcc_tty: Remove CONFIG_DCC_TTY driver

CONFIG_DCC_TTY driver is now superseded by CONFIG_HVC_DCC
driver and it is falling behind in terms of upstream
tty API changes. Remove it since everyone should use
HVC_DCC driver now.

Change-Id: I2ea72466d3fc119f931cb27da4c88522a624d4dc
Signed-off-by: Trilok Soni <tsoni@codeaurora.org>