integer-length for unsigned-byte 32 arg is slow

Describe the bug

Consider these functions:

(defun zot-u (n)
  (declare (type (unsigned-byte 32) n)
           (optimize (speed 3)))
  (integer-length n))
  
(defun zot-s (n)
  (declare (type (signed-byte 32) n)
           (optimize (speed 3)))
  (integer-length n)) 

To Reproduce

Steps to reproduce the behavior:

1. Compile zot-u and zot-s
2. Disassemble zot-u and zot-s
3. See that the disassembly of zot-s uses the BSR instruction to compute the result of integer-length
4. But note that zot-u doesn't and calls the integer-length function.

Expected behavior

zot-u should be able to use the BSR instruction to compute the integer-length of an (unsigned-byte 32) number.

Desktop (please complete the following information):

• OS: Any x86
• Version: 21d and probably everything earlier

Additional context

We need to define a new vop to handle integer-length when the arg is an (unsigned-byte 32) value.