staging: wilc1000: Replace function wilc_wlan_cfg_get_val()

staging: wilc1000: Replace function wilc_wlan_cfg_get_val()

Include wilc_wlan_cfg.h in wilc_netdev.c to enable it to call functions
in wilc_wlan_cfg.c.
Remove function wilc_wlan_cfg_get_val as all it does is call
wilc_wlan_cfg_get_wid_value in file wilc_wlan_cfg.c.
Rename function wilc_wlan_cfg_get_wid_value to wilc_wlan_cfg_get_val to
maintain compatibility with call sites (including in wilc_netdev.c).
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190712072009.2550-1-nishkadg.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>