arm: pxa: introducing cpuinfo display for marvell pxa270m

According to table 2-3 on page 87 of Marvell's latest PXA270
Specification Update Rev. I from 2010.04.19 [1] there exists a breed of
chips with a new CPU ID for PXA270M A1 stepping which our latest
Colibri PXA270 V2.4A modules actually have assembled. This patch helps
in correctly identifying those chips upon boot as well which then looks
as follows:

CPU: Marvell PXA27xM rev. A1

[1] http://www.marvell.com/application-processors/pxa-family/assets/pxa_27x_spec_update.pdf



Acked-by: Marek Vasut <marex@denx.de>