adb: cleanup some portions of client usb interfaces

Cleanup to remove open coded functions.

Test: build
Bug: 63736262
Bug: 38446744
Bug: 66912053
Change-Id: I3e6e5a22542934837b6a03523987141dc2776d48
diff --git a/client/usb_linux.cpp b/client/usb_linux.cpp
index a7df0ed..1f376a4 100644
--- a/client/usb_linux.cpp
+++ b/client/usb_linux.cpp
@@ -253,7 +253,7 @@
                             continue;
                         }
                             /* aproto 01 needs 0 termination */
-                        if (interface->bInterfaceProtocol == 0x01) {
+                        if (interface->bInterfaceProtocol == ADB_PROTOCOL) {
                             max_packet_size = ep1->wMaxPacketSize;
                             zero_mask = ep1->wMaxPacketSize - 1;
                         }