debugfs: add missing #ifdef HAS_IOMEM

"debugfs: add tools to printk 32-bit registers" adds new functions which rely
on IOMEM functionality which is not present on all architectures and therefore
result in compile errors:

fs/debugfs/file.c: In function 'debugfs_print_regs32':
fs/debugfs/file.c:561:7: error: implicit declaration of function 'readl' [-Werror=implicit-function-declaration]

Add an #ifdef CONFIG_HAS_IOMEM to fix this
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: NAlessandro Rubini <rubini@gnudd.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

fs/debugfs/file.c

@@ -528,6 +528,8 @@ struct dentry *debugfs_create_blob(const char *name, mode_t mode,
 }
 EXPORT_SYMBOL_GPL(debugfs_create_blob);
 
+#ifdef CONFIG_HAS_IOMEM
+
 /*
  * The regset32 stuff is used to print 32-bit registers using the
  * seq_file utilities. We offer printing a register set in an already-opened
@@ -616,3 +618,5 @@ struct dentry *debugfs_create_regset32(const char *name, mode_t mode,
 	return debugfs_create_file(name, mode, parent, regset, &fops_regset32);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_regset32);
+
+#endif /* CONFIG_HAS_IOMEM */