staging: rtl8723bs: hal: sdio_ops: Mark used 'err' as __maybe_unused and remove another

'err' is only used if debug is enabled.

Also remove 4 year old TODO.

Fixes the following W=1 kernel build warning(s):

 drivers/staging/rtl8723bs/hal/sdio_ops.c: In function ‘sdio_read32’:
 drivers/staging/rtl8723bs/hal/sdio_ops.c:170:6: warning: variable ‘err’ set but not used [-Wunused-but-set-variable]
 drivers/staging/rtl8723bs/hal/sdio_ops.c: In function ‘sdio_read_mem’:
 drivers/staging/rtl8723bs/hal/sdio_ops.c:381:6: warning: variable ‘err’ set but not used [-Wunused-but-set-variable]

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Fabio Aiuto <fabioaiuto83@gmail.com>
Cc: linux-staging@lists.linux.dev
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210414181129.1628598-47-lee.jones@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8723bs/hal/sdio_ops.c

@@ -160,7 +160,7 @@ static u32 sdio_read32(struct intf_hdl *intfhdl, u32 addr)
 	u32 ftaddr;
 	u8 shift;
 	u32 val;
-	s32 err;
+	s32 __maybe_unused err;
 	__le32 le_tmp;
 
 	adapter = intfhdl->padapter;
@@ -360,10 +360,7 @@ static void sdio_read_mem(
 	u8 *rmem
 )
 {
-	s32 err;
-
-	err = sdio_readN(intfhdl, addr, cnt, rmem);
-	/* TODO: Report error is err not zero */
+	sdio_readN(intfhdl, addr, cnt, rmem);
 }
 
 static void sdio_write_mem(