watchdog/hpwdt: Include nmi.h only if CONFIG_HPWDT_NMI_DECODING

Fixes: d48b0e17 ("x86, nmi, drivers: Fix nmi splitup build bug")

Arm64 does not support NMI and has no <asm/nmi.h>.

Include <asm/nmi.h> only if CONFIG_HPWDT_NMI_DECODING is defined to
avoid build failure on non-existent header file on Arm64.
Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220820202821.1263837-2-jerry.hoemann@hpe.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/hpwdt.c

@@ -20,7 +20,9 @@
 #include <linux/pci_ids.h>
 #include <linux/types.h>
 #include <linux/watchdog.h>
+#ifdef CONFIG_HPWDT_NMI_DECODING
 #include <asm/nmi.h>
+#endif
 #include <linux/crash_dump.h>
 
 #define HPWDT_VERSION			"2.0.4"