riscv: mm: init: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef

Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE" by a
check for "IS_ENABLED(CONFIG_KEXEC_CORE)", to simplify the code and
increase compile coverage.

Link: https://lkml.kernel.org/r/20211206160514.2000-3-jszhang@kernel.orgSigned-off-by: Jisheng Zhang <jszhang@kernel.org>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/riscv/mm/init.c

@@ -957,7 +957,6 @@ static inline void setup_vm_final(void)
 }
 #endif /* CONFIG_MMU */
 
-#ifdef CONFIG_KEXEC_CORE
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
  *
@@ -974,6 +973,8 @@ static void __init reserve_crashkernel(void)
 
 	int ret = 0;
 
+	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
+		return;
 	/*
 	 * Don't reserve a region for a crash kernel on a crash kernel
 	 * since it doesn't make much sense and we have limited memory
@@ -1023,7 +1024,6 @@ static void __init reserve_crashkernel(void)
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
 }
-#endif /* CONFIG_KEXEC_CORE */
 
 void __init paging_init(void)
 {
@@ -1037,9 +1037,7 @@ void __init misc_mem_init(void)
 	arch_numa_init();
 	sparse_init();
 	zone_sizes_init();
-#ifdef CONFIG_KEXEC_CORE
 	reserve_crashkernel();
-#endif
 	memblock_dump_all();
 }