HV: add the missing brackets to loop body

MISRA-C requires the use of brackets, even when there is only one
statement in the loop body.

Signed-off-by: Ying Liu <ying2.liu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/lib/string.c

@@ -150,8 +150,9 @@ int atoi(const char *str)
 
 char *strchr(const char *s, int ch)
 {
-	while ((*s != 0) && (*s != ch))
+	while ((*s != 0) && (*s != ch)) {
 		++s;
+	}
 
 	return ((*s) != 0) ? ((char *)s) : 0;
 }