soc: qcom: eud: Define dummy set_temios and get_mctrl callbacks

Apparently, serial core calls into the serial driver's .set_termios
and .get_mctrl uart_ops callbacks without checking if it exists or
not. Hence, implement a dummy definition of the callback to satisfy
the serial core.

Change-Id: Ic2e9eda5fb8b20be55c59f93ee05c2aa51a6362e
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>