rtlwifi: 8192de: make tables to be 'static const'

This can reduce code size 264 bytes, and make code more readable.

         text	   data	    bss	    dec	    hex	filename
Before: 13586	      0	     16	  13602	   3522	rtl8192de/dm.o
After:  13322	      0	     16	  13338	   341a	rtl8192de/dm.o

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>