Driver is using uint16_t and is encountering an overflow of the 16bits when
calculating link speed.

Fix by using a u32 type.
Signed-off-by: NDick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: NJames Smart <jsmart2021@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>