Use more standard types for manipulating pointers.

[jhb]

Summary

• Use a uintptr_t cast to get the virtual address of a pointer in USB_P2U() instead of a ptrdiff_t.

• Add offsets to a char * pointer directly without roundtripping the pointer through a ptrdiff_t in USB_ADD_BYTES().

[• hselasky]

Just make sure stand/usb builds too before committing.

[vidwer_fbsdbugs_gmail.com]

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