hal/sm_io/*/acq/sm_io_acq_exp.c: fix maximum channel error check

First, we need to check if the received argument is within the
valid range. Only later, we must proceed...

This fixes #33 github issue

hal/sm_io/modules/acq/sm_io_acq_exp.c

@@ -64,13 +64,6 @@ static int _acq_data_acquire (void *owner, void *args, void *ret)
     uint32_t num_samples = *(uint32_t *) EXP_MSG_ZMQ_FIRST_ARG(args);
     uint32_t chan = *(uint32_t *) EXP_MSG_ZMQ_NEXT_ARG(args);
 
-    /* number of samples required is out of the maximum limit */
-    if (num_samples > SMIO_ACQ_HANDLER(self)->acq_buf[chan].max_samples-1) {
-        DBE_DEBUG (DBG_SM_IO | DBG_LVL_WARN, "[sm_io:acq] data_acquire: "
-                "Number of samples required is out of the maximum limit\n");
-        return -ACQ_NUM_SAMPLES_OOR;
-    }
-
     /* channel required is out of the limit */
     if (chan > SMIO_ACQ_NUM_CHANNELS-1) {
         DBE_DEBUG (DBG_SM_IO | DBG_LVL_WARN, "[sm_io:acq] data_acquire: "
@@ -79,6 +72,13 @@ static int _acq_data_acquire (void *owner, void *args, void *ret)
         return -ACQ_NUM_SAMPLES_OOR;
     }
 
+    /* number of samples required is out of the maximum limit */
+    if (num_samples > SMIO_ACQ_HANDLER(self)->acq_buf[chan].max_samples-1) {
+        DBE_DEBUG (DBG_SM_IO | DBG_LVL_WARN, "[sm_io:acq] data_acquire: "
+                "Number of samples required is out of the maximum limit\n");
+        return -ACQ_NUM_SAMPLES_OOR;
+    }
+
     DBE_DEBUG (DBG_SM_IO | DBG_LVL_TRACE, "[sm_io:acq] data_acquire: "
             "Current acq params: number of samples = %u, channel = %u\n",
             num_samples, chan);