docs: marvell: update path in marvell documentation
docs: marvell: update path in marvell documentation

Change-Id: I0cebbaa900aa518700f13cbf02f8a97e0c76b21c
Signed-off-by: Grzegorz Jaszczyk <eca1ee760d6aeff8f14b7faabd6238ae79510d1f@semihalf.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware