sh: Move out individual boards without mach groups.

arch/sh/Makefile

arch/sh/boards/Kconfig

arch/sh/boards/Makefile

arch/sh/boards/board-ap325rxa.c

arch/sh/boards/board-magicpanelr2.c

arch/sh/boards/board-rsk7203.c

arch/sh/boards/board-sh7785lcr.c

arch/sh/boards/board-shmin.c

arch/sh/boards/mach-ap325rxa/Makefile

arch/sh/boards/mach-magicpanelr2/Kconfig

arch/sh/boards/mach-magicpanelr2/Makefile

arch/sh/boards/mach-rsk7203/Makefile

arch/sh/boards/mach-se/7619/Makefile

arch/sh/boards/mach-se/Makefile

arch/sh/boards/mach-se/board-se7619.c

arch/sh/boards/mach-sh7785lcr/Makefile

arch/sh/boards/mach-shmin/Makefile