usb: dwc2: Cleanup some checkpatch issues

This commmit is the result of running checkpatch --fix.

The results were verified for correctness. Some of the fixes result in
line over 80 char which we will fix manually later.

The following is a summary of what was done by checkpatch:
* Remove externs on function prototypes.
* Replace symbolic permissions with octal.
* Align code to open parens.
* Replace 'unsigned' with 'unsigned int'.
* Remove unneccessary blank lines.
* Add blank lines after declarations.
* Add spaces around operators.
* Remove unnecessary spaces after casts.
* Replace 'x == NULL' with '!x'.
* Replace kzalloc() with kcalloc().
* Concatenate multi-line strings.
* Use the BIT() macro.

Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
diff --git a/drivers/usb/dwc2/debug.h b/drivers/usb/dwc2/debug.h
index 12dbd1d..d3e52dd 100644
--- a/drivers/usb/dwc2/debug.h
+++ b/drivers/usb/dwc2/debug.h
@@ -17,8 +17,8 @@
 #include "core.h"
 
 #ifdef CONFIG_DEBUG_FS
-extern int dwc2_debugfs_init(struct dwc2_hsotg *);
-extern void dwc2_debugfs_exit(struct dwc2_hsotg *);
+int dwc2_debugfs_init(struct dwc2_hsotg *);
+void dwc2_debugfs_exit(struct dwc2_hsotg *);
 #else
 static inline int dwc2_debugfs_init(struct dwc2_hsotg *hsotg)
 {  return 0;  }