sh: init: use OF_EARLY_FLATTREE for early init

sh: init: use OF_EARLY_FLATTREE for early init

When CONFIG_OF_EARLY_FLATTREE and CONFIG_SH_DEVICE_TREE are not set,
SH3 build fails with a call to early_init_dt_scan(), so in
arch/sh/kernel/setup.c and arch/sh/kernel/head_32.S, use
CONFIG_OF_EARLY_FLATTREE instead of CONFIG_OF_FLATTREE.

Fixes this build error:
../arch/sh/kernel/setup.c: In function 'sh_fdt_init':
../arch/sh/kernel/setup.c:262:26: error: implicit declaration of function 'early_init_dt_scan' [-Werror=implicit-function-declaration]
  262 |         if (!dt_virt || !early_init_dt_scan(dt_virt)) {

Fixes: 03767daa1387 ("sh: fix build regression with CONFIG_OF && !CONFIG_OF_FLATTREE")
Fixes: eb6b6930a70f ("sh: fix memory corruption of unflattened device tree")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Suggested-by: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: devicetree@vger.kernel.org
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: linux-sh@vger.kernel.org
Cc: stable@vger.kernel.org
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/20230306040037.20350-4-rdunlap@infradead.org
Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>