sh: remove support for sh73180 and solution engine 73180

This patch removes old dead code:
- kill off sh73180 cpu support
- get rid of broken solution engine 73180 board support

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/mm/Kconfig

@@ -202,10 +202,6 @@ config CPU_SUBTYPE_SHX3
 
 # SH4AL-DSP Processor Support
 
-config CPU_SUBTYPE_SH73180
-	bool "Support SH73180 processor"
-	select CPU_SH4AL_DSP
-
 config CPU_SUBTYPE_SH7343
 	bool "Support SH7343 processor"
 	select CPU_SH4AL_DSP