hfsplus: remove unnecessary variable initialization

hfsplus: remove unnecessary variable initialization

Variables are assigned first and then used.  Initialization is not
required.

[akpm@linux-foundation.org: give hfsplus_listxattr:key_len narrower scope]
Link: https://lkml.kernel.org/r/20221221032119.10037-1-xupengfei@nfschina.com
Signed-off-by: XU pengfei <xupengfei@nfschina.com>
Reviewed-by: Andrew Morton <akpm@linux-foudation.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>