loongarch/kexec: refactor for kernel/Kconfig.kexec

The kexec and crash kernel options are provided in the common
kernel/Kconfig.kexec. Utilize the common options and provide
the ARCH_SUPPORTS_ and ARCH_SELECTS_ entries to recreate the
equivalent set of KEXEC and CRASH options.

Link: https://lkml.kernel.org/r/20230712161545.87870-7-eric.devolder@oracle.comSigned-off-by: Eric DeVolder <eric.devolder@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/loongarch/Kconfig

@@ -538,28 +538,16 @@ config CPU_HAS_PREFETCH
 	bool
 	default y
 
-config KEXEC
-	bool "Kexec system call"
-	select KEXEC_CORE
-	help
-	  kexec is a system call that implements the ability to shutdown your
-	  current kernel, and to start another kernel.  It is like a reboot
-	  but it is independent of the system firmware.   And like a reboot
-	  you can start any kernel with it, not just Linux.
+config ARCH_SUPPORTS_KEXEC
+	def_bool y
 
-	  The name comes from the similarity to the exec system call.
+config ARCH_SUPPORTS_CRASH_DUMP
+	def_bool y
 
-config CRASH_DUMP
-	bool "Build kdump crash kernel"
+config ARCH_SELECTS_CRASH_DUMP
+	def_bool y
+	depends on CRASH_DUMP
 	select RELOCATABLE
-	help
-	  Generate crash dump after being started by kexec. This should
-	  be normally only set in special crash dump kernels which are
-	  loaded in the main kernel with kexec-tools into a specially
-	  reserved region and then later executed after a crash by
-	  kdump/kexec.
-
-	  For more details see Documentation/admin-guide/kdump/kdump.rst
 
 config RELOCATABLE
 	bool "Relocatable kernel"