libmisc/csrand.c: Update comments

Those comments were written when this function used 64 bits (and
temporary variables of 128 bits).  Now it uses 32 bits, with temporaries
of 64 bits, so some values have changed.

Fixes: 2a61122b5e ("Unoptimize the higher part of the domain of csrand_uniform()")
Signed-off-by: Alejandro Colomar <alx@kernel.org>

libmisc/csrand.c

@@ -110,15 +110,15 @@ csrand_uniform32(uint32_t n)
 	if (n == 0)
 		return csrand();
 
-	bound = -n % n;  // analogous to `2^64 % n`, since `x % y == (x-y) % y`
+	bound = -n % n;  // analogous to `2^32 % n`, since `x % y == (x-y) % y`
 
 	do {
 		r = csrand();
 		mult = r * n;
-		rem = mult;  // analogous to `mult % 2^64`
-	} while (rem < bound);  // p = (2^64 % n) / 2^64;  W.C.: n=2^63+1, p=0.5
+		rem = mult;  // analogous to `mult % 2^32`
+	} while (rem < bound);  // p = (2^32 % n) / 2^32;  W.C.: n=2^31+1, p=0.5
 
-	r = mult >> WIDTHOF(n);  // analogous to `mult / 2^64`
+	r = mult >> WIDTHOF(n);  // analogous to `mult / 2^32`
 
 	return r;
 }