powerpc/fadump: cleanup crash memory ranges support

Commit 1bd6a1c4b80a ("powerpc/fadump: handle crash memory ranges array
index overflow") changed crash memory ranges to a dynamic array that
is reallocated on-demand with krealloc(). The relevant header for this
call was not included. The kernel compiles though. But be cautious and
add the header anyway.

Also, memory allocation logic in fadump_add_crash_memory() takes care
of memory allocation for crash memory ranges in all scenarios. Drop
unnecessary memory allocation in fadump_setup_crash_memory_ranges().

Fixes: 1bd6a1c4b80a ("powerpc/fadump: handle crash memory ranges array index overflow")
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/fadump.c

@@ -34,6 +34,7 @@
 #include <linux/crash_dump.h>
 #include <linux/kobject.h>
 #include <linux/sysfs.h>
+#include <linux/slab.h>
 
 #include <asm/debugfs.h>
 #include <asm/page.h>
@@ -1019,13 +1020,6 @@ static int fadump_setup_crash_memory_ranges(void)
 	pr_debug("Setup crash memory ranges.\n");
 	crash_mem_ranges = 0;
 
-	/* allocate memory for crash memory ranges for the first time */
-	if (!max_crash_mem_ranges) {
-		ret = allocate_crash_memory_ranges();
-		if (ret)
-			return ret;
-	}
-
 	/*
 	 * add the first memory chunk (RMA_START through boot_memory_size) as
 	 * a separate memory chunk. The reason is, at the time crash firmware