MIPS: Fix boot on Fuloong2 systems

Commit 268a2d60 ("MIPS: Loongson64: Rename CPU TYPES") changed
Kconfig symbols as follows:
	CPU_LOONGSON2 to CPU_LOONGSON2EF
	CPU_LOONGSON3 to CPU_LOONGSON64
	SYS_HAS_CPU_LOONGSON3 to SYS_HAS_CPU_LOONGSON64

It did not touch SYS_HAS_CPU_LOONGSON2E or SYS_HAS_CPU_LOONGSON2F.
However, the patch changed a conditional from

 #if defined(CONFIG_SYS_HAS_CPU_LOONGSON2E) || \
     defined(CONFIG_SYS_HAS_CPU_LOONGSON2F)

to

 #if defined(CONFIG_SYS_HAS_CPU_LOONGSON2EF)

SYS_HAS_CPU_LOONGSON2EF does not exist, resulting in boot failures
with the qemu fulong2e emulation. Revert to the original code.

Fixes: 268a2d60 ("MIPS: Loongson64: Rename CPU TYPES")
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org