Bluetooth HAL: Fail loudly on a write failure

Bug: 205758693
Test: VtsHalBluetoothTargetTest
Change-Id: I2151b324247a83a454b81c28c9f0f5cd5581be09
diff --git a/bluetooth/hci/h4_protocol.cc b/bluetooth/hci/h4_protocol.cc
index 97ba7aa..51a624f 100644
--- a/bluetooth/hci/h4_protocol.cc
+++ b/bluetooth/hci/h4_protocol.cc
@@ -58,10 +58,8 @@
   while (1) {
     ret = TEMP_FAILURE_RETRY(writev(uart_fd_, iov, 2));
     if (ret == -1) {
-      if (errno == EAGAIN) {
-        ALOGE("%s error writing to UART (%s)", __func__, strerror(errno));
-        continue;
-      }
+      LOG_ALWAYS_FATAL("%s error writing to UART (%s)", __func__,
+                       strerror(errno));
     } else if (ret == 0) {
       // Nothing written :(
       ALOGE("%s zero bytes written - something went wrong...", __func__);