mwifiex: rename mwifiex_free_adapter() routine in init.c

mwifiex: rename mwifiex_free_adapter() routine in init.c

We have two different static routines with name
mwifiex_free_adapter(). The routine in main.c actually frees the
adapter structure.

We will rename other routine in init.c to mwifiex_adapter_cleanup()
to avoid confusion.

BUG=None
TEST="iwlist mlan0 scan & sleep 1; rmmod mwifiex_sdio";
"echo scan > /sys/kernel/debug/kmemleak; cat /sys/kernel/debug/kmemleak"

Change-Id: I84933ea996d6d0f6568b2ae915ade5214e25790a
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Reviewed-on: https://gerrit.chromium.org/gerrit/50684
Reviewed-by: Paul Stewart <pstew@chromium.org>