bluetooth: host: Update FAE table type for HCI commands

Update FAE table type from array of uint8_t to int8_t. From Vol 6.0,
Part B, section 2.4.2.52: "The ChFAE field contains the per-channel
mode-0 FAE table of the local Controller. Every per-channel mode-0
FAE value is represented by an 8-bit signed integer"

Signed-off-by: Adam Cavender <adam.cavender@nordicsemi.no>