ARM: shmobile: henninger: add QSPI DT support

Define the Henninger board dependent part of the QSPI device node.
Add device nodes for Spansion S25FL512S SPI flash and MTD partitions on it.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>