x86/vhpet: address violations of MISRA C Rule 20.7

MISRA C Rule 20.7 states: "Expressions resulting from the expansion
of macro parameters shall be enclosed in parentheses". Therefore, some
macro definitions should gain additional parentheses to ensure that all
current and future users will be safe with respect to expansions that
can possibly alter the semantics of the passed-in macro parameter.

No functional change.

Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/hvm/hpet.c

@@ -43,11 +43,11 @@
     ((s_time_t)((((tick) > (h)->hpet_to_ns_limit) ?     \
         ~0ULL : (tick) * (h)->hpet_to_ns_scale) >> 10))
 
-#define timer_config(h, n)       (h->hpet.timers[n].config)
+#define timer_config(h, n)       ((h)->hpet.timers[n].config)
 #define timer_enabled(h, n)      (timer_config(h, n) & HPET_TN_ENABLE)
 #define timer_is_periodic(h, n)  (timer_config(h, n) & HPET_TN_PERIODIC)
 #define timer_is_32bit(h, n)     (timer_config(h, n) & HPET_TN_32BIT)
-#define hpet_enabled(h)          (h->hpet.config & HPET_CFG_ENABLE)
+#define hpet_enabled(h)          ((h)->hpet.config & HPET_CFG_ENABLE)
 #define timer_level(h, n)        (timer_config(h, n) & HPET_TN_LEVEL)
 
 #define timer_int_route(h, n)    MASK_EXTR(timer_config(h, n), HPET_TN_ROUTE)