powerpc: Change places using CONFIG_KEXEC to use CONFIG_KEXEC_CORE instead.

Commit 2965faa5e0 ("kexec: split kexec_load syscall from kexec core
code") introduced CONFIG_KEXEC_CORE so that CONFIG_KEXEC means whether
the kexec_load system call should be compiled-in and CONFIG_KEXEC_FILE
means whether the kexec_file_load system call should be compiled-in.
These options can be set independently from each other.

Since until now powerpc only supported kexec_load, CONFIG_KEXEC and
CONFIG_KEXEC_CORE were synonyms. That is not the case anymore, so we
need to make a distinction. Almost all places where CONFIG_KEXEC was
being used should be using CONFIG_KEXEC_CORE instead, since
kexec_file_load also needs that code compiled in.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/cell/spu_base.c

@@ -676,7 +676,7 @@ static ssize_t spu_stat_show(struct device *dev,
 
 static DEVICE_ATTR(stat, 0444, spu_stat_show, NULL);
 
-#ifdef CONFIG_KEXEC
+#ifdef CONFIG_KEXEC_CORE
 
 struct crash_spu_info {
 	struct spu *spu;