ARM: shmobile: sh7372: Remove Legacy C SoC code

Remove support for the legacy Cortex-A8 based sh7372 SoC.

The Linux kernel still lacks DT bindings for the sh7372 INTC
interrupt controller so DT multiplatform support is not possibile.

Also, the sh7372 SoC never went into mass production anyway so to
aid migration to DT multiplatform simply get rid of sh7372 support.

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>