Remove not valid UTF-8 characters

These UTF-8 characters are causing issues with static code analysis
tools.

Error: encoding error in ./lib/crypt/zuc.c
'utf-8' codec can't decode byte 0x97 in position 3948: invalid start byte
Python3 requires input character data to be perfectly encoded;
it also requires perfectly correct system encoding settings.
Unfortunately, your data and/or system settings are not.

lib/crypt/zuc.c

@@ -91,8 +91,7 @@ static u32 EK_d[16] = {
 0x4D78, 0x2F13, 0x6BC4, 0x1AF1, 0x5E26, 0x3C4D, 0x789A, 0x47AC
 };
 
-/* ——————————————————————- */ 
-/* c = a + b mod (2^31 – 1) */
+/* c = a + b mod (2^31 - 1) */
 u32 AddM(u32 a, u32 b)
 {
 	u32 c = a + b;