initvals: Add "-h" as a help option

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
initvals: Mention what -w does

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
initvals: Update checksums

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
initvals: Override AR9580 MAC postamble

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
initvals: Override AR9580 MAC core

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>