staging: rtl8188eu: Fix potential NULL pointer dereference of kcalloc

[ Upstream commit 7671ce0d92933762f469266daf43bd34d422d58c ]

hwxmits is allocated via kcalloc and not checked for failure before its
dereference. The patch fixes this problem by returning error upstream
in rtl8723bs, rtl8188eu.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Acked-by: Mukesh Ojha <mojha@codeaurora.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>