gbsim/uart: Fix compilation warning in escape parsing
gbsim/uart: Fix compilation warning in escape parsing

Commit 24f7dec263df ('gbsim/uart: Add support for UART error signals')
contains a switch statement that can generate a compile warning.
This patch changes the offending data type to mitigate the warning.

Signed-off-by: Bryan O'Donoghue <165dc05575478af93ac2f97f67be6e1756010094@linaro.org>
Suggested-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@google.com>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@google.com>

bcousson/gbsim,gregkh/gbsim,gregkh/gbsim,projectara/gbsim,bcousson/gbsim,projectara/gbsim,bcousson/gbsim