Dumpsys: fix native flag output

flag with 1 letter capitalize were not displayed correctly

fooXBar was displayed as foo_xbar instead of foo_x_bar

Bug: 321313362
Test: m . | adb shell dumpsys bluetooth_manager
Flag: Exempt, debug tool only
Change-Id: I955631da30af8ccb50d26a9458dadfd2a70dc4d3