ARM: dts: Add openbmc-flash-layout-64-alt.dtsi

Add openbmc-flash-layout-64-alt.dtsi to describe the partitions of the
secondary flash for OpenBMC's 64M static layout.
The layout is the same as openbmc-flash-layout-64.dtsi and the labels
are prepended with "alt-" for the partitions.

Signed-off-by: Lei YU <yulei.sh@bytedance.com>
Reviewed-by: Patrick Williams <patrick@stwcx.xyz>
Link: https://lore.kernel.org/r/20211210093443.2140557-1-yulei.sh@bytedance.com


Signed-off-by: Joel Stanley <joel@jms.id.au>