x86/boot/acpi: Move get_cmdline_acpi_rsdp() under #ifdef guard

When building with "EXTRA_CFLAGS=-Wall" gcc warns:

arch/x86/boot/compressed/acpi.c:29:30: warning: get_cmdline_acpi_rsdp defined but not used [-Wunused-function]

get_cmdline_acpi_rsdp() is only used when CONFIG_RANDOMIZE_BASE and
CONFIG_MEMORY_HOTREMOVE are both enabled, so any build where one of these
config options is disabled has this issue.

Move the function under the same ifdef guard as the call site.

[ tglx: Add context to the changelog so it becomes useful ]

Fixes: 41fa1ee ("acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1569719633-32164-1-git-send-email-zhenzhong.duan@oracle.com

arch/x86/boot/compressed/acpi.c

@@ -20,30 +20,6 @@
  */
 struct mem_vector immovable_mem[MAX_NUMNODES*2];
 
-/*
- * Max length of 64-bit hex address string is 19, prefix "0x" + 16 hex
- * digits, and '\0' for termination.
- */
-#define MAX_ADDR_LEN 19
-
-static acpi_physical_address get_cmdline_acpi_rsdp(void)
-{
-	acpi_physical_address addr = 0;
-
-#ifdef CONFIG_KEXEC
-	char val[MAX_ADDR_LEN] = { };
-	int ret;
-
-	ret = cmdline_find_option("acpi_rsdp", val, MAX_ADDR_LEN);
-	if (ret < 0)
-		return 0;
-
-	if (kstrtoull(val, 16, &addr))
-		return 0;
-#endif
-	return addr;
-}
-
 /*
  * Search EFI system tables for RSDP.  If both ACPI_20_TABLE_GUID and
  * ACPI_TABLE_GUID are found, take the former, which has more features.
@@ -298,6 +274,30 @@ acpi_physical_address get_rsdp_addr(void)
 }
 
 #if defined(CONFIG_RANDOMIZE_BASE) && defined(CONFIG_MEMORY_HOTREMOVE)
+/*
+ * Max length of 64-bit hex address string is 19, prefix "0x" + 16 hex
+ * digits, and '\0' for termination.
+ */
+#define MAX_ADDR_LEN 19
+
+static acpi_physical_address get_cmdline_acpi_rsdp(void)
+{
+	acpi_physical_address addr = 0;
+
+#ifdef CONFIG_KEXEC
+	char val[MAX_ADDR_LEN] = { };
+	int ret;
+
+	ret = cmdline_find_option("acpi_rsdp", val, MAX_ADDR_LEN);
+	if (ret < 0)
+		return 0;
+
+	if (kstrtoull(val, 16, &addr))
+		return 0;
+#endif
+	return addr;
+}
+
 /* Compute SRAT address from RSDP. */
 static unsigned long get_acpi_srat_table(void)
 {