HV: lib: make the argument to udelay unsigned

The parameter to udelay is the microseconds to wait for, which should be an
unsigned integer.

Signed-off-by: Junjie Mao <junjie.mao@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/include/lib/rtl.h

@@ -26,7 +26,7 @@ struct udiv_result {
 };
 
 /* Function prototypes */
-void udelay(int us);
+void udelay(uint32_t us);
 void *memchr(const void *void_s, int c, size_t n);
 void *memmove(void *s1, const void *s2, size_t n);
 int strcmp(const char *s1, const char *s2);