rtlwifi: rtl8723be: constify pci_device_id.

pci_device_id are not supposed to change at runtime. All functions
working with pci_device_id provided by <linux/pci.h> work with
const pci_device_id. So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   3032	    912	      0	   3944	    f68	realtek/rtlwifi/rtl8723be/sw.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   3096	    848	      0	   3944	    f68	realtek/rtlwifi/rtl8723be/sw.o
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtlwifi/rtl8723be/sw.c

@@ -375,7 +375,7 @@ static const struct rtl_hal_cfg rtl8723be_hal_cfg = {
 	.maps[RTL_RC_HT_RATEMCS15] = DESC92C_RATEMCS15,
 };
 
-static struct pci_device_id rtl8723be_pci_ids[] = {
+static const struct pci_device_id rtl8723be_pci_ids[] = {
 	{RTL_PCI_DEVICE(PCI_VENDOR_ID_REALTEK, 0xB723, rtl8723be_hal_cfg)},
 	{},
 };