of: unittest: remove unneeded semicolon

Eliminate the following coccicheck warning:
./drivers/of/unittest.c:1961:2-3: Unneeded semicolon

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220107002826.77939-1-yang.lee@linux.alibaba.com