Ignore disabled Kinetis USB endpoint interrupts

Ignore interrupts on disabled USB endpoints. This prevents handling
interrupts when in the wrong state.

Prior to this patch when running the serial test on a K64F the assert
on line 908 of USBDevice.cpp would sometimes be triggered. This
assert indicates that an endpoint 0 IN interrupt occurred before
the device was ready.

This occurs during the test_cdc_usb_reconnect test when the host sends
a "Set Control Line State" USB request and the device acknowledges it
just before USB is disconnected.

Author: c1728p9

usb/device/targets/TARGET_Freescale/USBPhy_Kinetis.cpp

@@ -636,8 +636,11 @@ void USBPhyHw::process()
         uint32_t ev_odd = (USB0->STAT >> 2) & 0x01;
         int phy_ep = (num << 1) | dir;
 
+        bool tx_en = (USB0->ENDPOINT[PHY_TO_LOG(phy_ep)].ENDPT & USB_ENDPT_EPTXEN_MASK) ? true : false;
+        bool rx_en = (USB0->ENDPOINT[PHY_TO_LOG(phy_ep)].ENDPT & USB_ENDPT_EPRXEN_MASK) ? true : false;
+
         // setup packet
-        if ((num == 0) && (TOK_PID((EP_BDT_IDX(num, dir, ev_odd))) == SETUP_TOKEN)) {
+        if (tx_en && (num == 0) && (TOK_PID((EP_BDT_IDX(num, dir, ev_odd))) == SETUP_TOKEN)) {
             setup_suspend = true;
             Data1 |= 0x02 | 0x01; // set DATA1 for TX and RX
             bdt[EP_BDT_IDX(0, TX, EVEN)].info &= ~BD_OWN_MASK;
@@ -648,7 +651,7 @@ void USBPhyHw::process()
 
         } else {
             // OUT packet
-            if (TOK_PID((EP_BDT_IDX(num, dir, ev_odd))) == OUT_TOKEN) {
+            if (rx_en && (TOK_PID((EP_BDT_IDX(num, dir, ev_odd))) == OUT_TOKEN)) {
                 if (num == 0)
                     events->ep0_out();
                 else {
@@ -658,7 +661,7 @@ void USBPhyHw::process()
             }
 
             // IN packet
-            if (TOK_PID((EP_BDT_IDX(num, dir, ev_odd))) == IN_TOKEN) {
+            if (tx_en && (TOK_PID((EP_BDT_IDX(num, dir, ev_odd))) == IN_TOKEN)) {
                 if (num == 0) {
                     events->ep0_in();
                     if (set_addr == 1) {