staging: rtlwifi: shut up -Wmaybe-uninitialized warning

This function contains a series of interdependent conditions,
slightly more than gcc can follow handle apparently:

drivers/staging/rtlwifi/base.c: In function 'rtl_check_beacon_key':
drivers/staging/rtlwifi/base.c:2546:34: error: 'ht_cap_ie' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This moves the code around a bit, to simplify the conditions
enough that gcc can see that all variables are correctly
initialized.

Fixes: 56bde846 ("staging: r8822be: Add existing rtlwifi and rtl_pci parts for new driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>