tty: serial: atmel: Add COMMON_CLK dependency to SERIAL_ATMEL

tty: serial: atmel: Add COMMON_CLK dependency to SERIAL_ATMEL

Now that the driver makes use of `__clk_is_enabled()` in order to
know whether a `clk_disable_unprepare()` is needed or not on the
GCLK, a new dependency has been introduced: COMMON_CLK. If this
`CONFIG_COMMON_CLK` is not enabled, whatever config may have this
driver enabled without COMMON_CLK then an undefined reference to
`__clk_is_enabled()` will be issued by the linker.

Thus, make sure that, unless `CONFIG_COMMON_CLK` is enabled, this
driver is not compiled.

Fixes: 54b409cb4036 ("tty: serial: atmel: Make the driver aware of the existence of GCLK")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sergiu Moga <sergiu.moga@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20220926143244.485578-1-sergiu.moga@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>