platsupport,imx: Return ETIME when time in past

The epit and ltimer implementations for imx need to return an error when
asked to set a timeout not far enough into the future that it either
rounds down to 0 or underflows.

Signed-off-by: Kent McLeod <kent@kry10.com>

libplatsupport/src/mach/imx/epit/epit.c

diff --git a/libplatsupport/src/mach/imx/epit/epit.c b/libplatsupport/src/mach/imx/epit/epit.c
index f38fea9..21c64e9 100644
--- a/libplatsupport/src/mach/imx/epit/epit.c
+++ b/libplatsupport/src/mach/imx/epit/epit.c
@@ -143,6 +143,9 @@
     /* Set counter modulus - this effectively sets the timeouts to us but doesn't
      * overflow as fast. */
     uint64_t counterValue = (uint64_t)(IPG_FREQ / (epit->prescaler + 1)) * (ns / 1000ULL);
+    if (counterValue == 0) {
+        return ETIME;
+    }
 
     return epit_set_timeout_ticks(epit, counterValue, periodic);
 }

libplatsupport/src/mach/imx/ltimer.c

diff --git a/libplatsupport/src/mach/imx/ltimer.c b/libplatsupport/src/mach/imx/ltimer.c
index 5d672a7..588be1b 100644
--- a/libplatsupport/src/mach/imx/ltimer.c
+++ b/libplatsupport/src/mach/imx/ltimer.c
@@ -46,6 +46,9 @@
 
     if (type == TIMEOUT_ABSOLUTE) {
         uint64_t current_time = imx_get_time(&imx_ltimer->timers);
+        if (ns < current_time) {
+            return ETIME;
+        }
         ns -= current_time;
     }