octeontx2-af: Remove redundant initialization of variable pin

The variable pin is being initialized with a value that is never
read, it is being updated later on in only one case of a switch
statement.  The assignment is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>