Use UL functions for Qm/R determination

During refactoring, the wrong functions and correspondingly tables have
been used to calculate UL TB size. Fix through correct functions.

This should fix these error messages:

    3624774.778195 [MAC]    E (nr_get_Qm_dl:2034)             Invalid MCS table index 3 (expected in range [0,2])
    3624774.778207 [MAC]    E (nr_get_code_rate_dl:2066)      Invalid MCS table index 3 (expected in range [0,2])
    3624774.778211 [NR_MAC] E (nr_compute_tbs:63)             Error in compute TBS with a NULL input, returning NULL TBS

Fixes: 9449f777 ("Remove TBS table and recompute on demand")

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c

@@ -2081,8 +2081,8 @@ static int  pf_ul(gNB_MAC_INST *nrmac,
 
     /* Create UE_sched for UEs eligibale for new data transmission*/
     /* Calculate coefficient*/
-    const uint8_t Qm = nr_get_Qm_dl(selected_mcs, current_BWP->mcs_table);
-    const uint16_t R = nr_get_code_rate_dl(selected_mcs, current_BWP->mcs_table);
+    const uint8_t Qm = nr_get_Qm_ul(selected_mcs, current_BWP->mcs_table);
+    const uint16_t R = nr_get_code_rate_ul(selected_mcs, current_BWP->mcs_table);
     const uint32_t tbs = nr_compute_tbs(Qm,
                                         R,
                                         1, /* rbSize */