staging: rtl8723bs: Improve clarity of MAR usage

This patch improves the readability of the code related to the Multicast
Address Register (REG_MAR) in the rtl8723bs driver. It adds comments to
clarify the purpose and offset of the register, making the code more
self-documenting without introducing new macros.

Signed-off-by: Manjae Cho <[e-mail]>
Reviewed-by: Philipp Hortmann <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/rtl8723bs/hal/sdio_halinit.c

···
 	rtw_write32(padapter, REG_RCR, pHalData->ReceiveConfig);
 
 	/*  Accept all multicast address */
-	rtw_write32(padapter, REG_MAR, 0xFFFFFFFF);
-	rtw_write32(padapter, REG_MAR + 4, 0xFFFFFFFF);
+	rtw_write32(padapter, REG_MAR, 0xFFFFFFFF);	/* Offset 0x0620-0x0623 */
+	rtw_write32(padapter, REG_MAR + 4, 0xFFFFFFFF);	/* Offset 0x0624-0x0627 */
 
 	/*  Accept all data frames */
 	value16 = 0xFFFF;