staging:rtl8712: Fix sparse warning incorrect type in assignment

This patch fixes the following sparse warnings:

drivers/staging/rtl8712/rtl871x_cmd.c:471:30: warning: incorrect type in
assignment (different base types)
drivers/staging/rtl8712/rtl871x_cmd.c:471:30:    expected unsigned int
[unsigned] [usertype] Length
drivers/staging/rtl8712/rtl871x_cmd.c:471:30:    got restricted __le32
[usertype] <noident>
drivers/staging/rtl8712/rtl871x_cmd.c:472:32: warning: incorrect type in
assignment (different base types)
drivers/staging/rtl8712/rtl871x_cmd.c:472:32:    expected unsigned int
[unsigned] [usertype] IELength
drivers/staging/rtl8712/rtl871x_cmd.c:472:32:    got restricted __le32
[usertype] <noident>
drivers/staging/rtl8712/rtl871x_cmd.c:473:39: warning: incorrect type in
assignment (different base types)
drivers/staging/rtl8712/rtl871x_cmd.c:473:39:    expected unsigned int
[unsigned] [usertype] SsidLength
drivers/staging/rtl8712/rtl871x_cmd.c:473:39:    got restricted __le32
[usertype] <noident>

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>