m68k: mm: Include <asm/hwtest.h> for hwreg_()

When building with W=1:

arch/m68k/mm/hwtest.c:29:5: warning: no previous prototype for ‘hwreg_present’ [-Wmissing-prototypes]
29 | int hwreg_present(volatile void *regp)
| ^~~~~~~~~~~~~
arch/m68k/mm/hwtest.c:62:5: warning: no previous prototype for ‘hwreg_write’ [-Wmissing-prototypes]
62 | int hwreg_write(volatile void *regp, unsigned short val)
| ^~~~~~~~~~~

Fix this by including <asm/hwtest.h>.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/m68k/mm/hwtest.c

···
 
 #include <linux/module.h>
 
+#include <asm/hwtest.h>
+
 int hwreg_present(volatile void *regp)
 {
 	int ret = 0;