USB / dwc3: Fix a checkpatch warning in core.c

This patch fixes the following checkpatch.pl warning in core.c:
    WARNING: braces {} are not necessary for any arm of this statement

Signed-off-by: Kushagra Verma <kushagra765@outlook.com>
Link: https://lore.kernel.org/r/TYZPR01MB39354534E2F9EE4E022DDAFFF8C89@TYZPR01MB3935.apcprd01.prod.exchangelabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>