mwifiex: Removed unused 'pkt_type' variable

Commit 92263a84 introduced mwifiex_deaggr_sdio_pkt which initializes
variable pkt_type but does not use it. Compiling with W=1 gives the following
warning, fix it.
mwifiex/sdio.c: In function ‘mwifiex_deaggr_sdio_pkt’:
mwifiex/sdio.c:1198:6: warning: variable ‘pkt_type’ set but not used [-Wunused-but-set-variable]

Fixes: 92263a84 ("mwifiex: add SDIO rx single port aggregation")
Cc: Zhaoyang Liu <liuzy@marvell.com>
Cc: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kirtika Ruchandani <kirtika@google.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>