wl18xx: Fix Wunused-const-variable

Clang produces the following warning

drivers/net/wireless/ti/wl18xx/main.c:1850:43: warning: unused variable
'wl18xx_iface_ap_cl_limits' [-Wunused-const-variable] static const struct
ieee80211_iface_limit wl18xx_iface_ap_cl_limits[] = { ^
drivers/net/wireless/ti/wl18xx/main.c:1869:43: warning: unused variable
'wl18xx_iface_ap_go_limits' [-Wunused-const-variable] static const struct
ieee80211_iface_limit wl18xx_iface_ap_go_limits[] = { ^

The commit that added these variables never used them. Removing them.

Cc: clang-built-linux@googlegroups.com
Link: https://github.com/ClangBuiltLinux/linux/issues/530
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>