Add check on length of name.

[celine-lee]

My team and I were looking through the Ventoy source code using our AI-based source code anomaly detection tool, MP-CodeCheck, and found this line that we think may benefit from a slight adjustment for the sake of maintainability: a check on the length of the string variable name before checking its first three characters.

We believe that this string length check helps as a safeguard against undefined behavior with the string character checking.

[ventoy]

IMHO, the check is unnecessary because of short-circuiting in if statement.