qlcnic: remove redundant assignment to variable index

Variable index is being assigned a value that is never read, it is being
re-assigned later in a following for-loop. The assignment is redundant
and can be removed.

Cleans up clang scan build warning:
drivers/net/ethernet/qlogic/qlcnic/qlcnic_ethtool.c:1358:17: warning:
Although the value stored to 'index' is used in the enclosing expression,
the value is never actually read from 'index' [deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20220318012035.89482-1-colin.i.king@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>