Added init script /etc/init.d/S70wrs_auxclk to start wrs_auxclk with parameters
read from dot-config.

Added parameters to Kconfig:
--WRSAUXCLK_FREQ
--WRSAUXCLK_DUTY
--WRSAUXCLK_CSHIFT
--WRSAUXCLK_SIGDEL
--WRSAUXCLK_PPSHIFT
All above are used as parameters to wrs_auxclk,
which configure external clock clk2

NOTE: This patch requires new Gateware! wrs_auxclk will hang switch when using
gateware from last release of switch.
Signed-off-by: Adam Wujek <adam.wujek@cern.ch>