wl12xx: fix use after free

wl12xx: fix use after free

When DEBUG_SPI is included in the debug log level wl1271_spi_reset()
will dump the already freed memory instead of the SPI buffer.

This bug was spotted by the semantic patch tool coccinelle using the
script found at scripts/coccinelle/free/kfree.cocci.

More information about semantic patching is available at
http://coccinelle.lip6.fr/

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>