speakup: replace utils' u_char with unsigned char

commit 92ca969 upstream.

drivers/accessibility/speakup/utils.h will be used to compile host tool
to generate metadata.

"u_char" is a non-standard type, which is defined to "unsigned char"
on glibc but not defined by some libc, e.g. musl.

Let's replace "u_char" with "unsigned char"

Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: stable <stable@kernel.org>
Link: https://lore.kernel.org/r/b75743026aaee2d81efe3d7f2e8fa47f7d0b8ea7.1665736571.git.congdanhqx@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/accessibility/speakup/utils.h

@@ -54,7 +54,7 @@ static inline int oops(const char *msg, const char *info)
 
 static inline struct st_key *hash_name(char *name)
 {
-	u_char *pn = (u_char *)name;
+	unsigned char *pn = (unsigned char *)name;
 	int hash = 0;
 
 	while (*pn) {