linux-phytec-ti

wil6210: fix warning in pointer arithmetic

In some compilation environments, result of pointer arithmetic interpreted as int
while in others it is long int. Force conversion to long.

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>