staging: rtlwifi: rtl8822b: fix to avoid potential NULL pointer dereference

skb allocated via dev_alloc_skb can fail and return a NULL pointer.
This patch avoids such a scenario and returns, consistent with other
invocations.
Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtlwifi/rtl8822be/fw.c

@@ -743,6 +743,8 @@ void rtl8822be_set_fw_rsvdpagepkt(struct ieee80211_hw *hw, bool b_dl_finished)
 		      u1_rsvd_page_loc, 3);
 
 	skb = dev_alloc_skb(totalpacketlen);
+	if (!skb)
+		return;
 	memcpy((u8 *)skb_put(skb, totalpacketlen), &reserved_page_packet,
 	       totalpacketlen);