Wi-Fi: @IntRange for getRx/TxLinkSpeedMbps

Added from range for getters getRxLinkSpeedMbps/getTxLinkSpeedMbps.

Bug: 124302657
Test: Connect STA to AP and verify the link speeds in network details.
Change-Id: I0b541c592ef80e6907c528879450c5be7bdc3d9d