ipmi: Fix memory leak in __ipmi_bmc_register

In the impelementation of __ipmi_bmc_register() the allocated memory for
bmc should be released in case ida_simple_get() fails.

Fixes: 68e7e50f ("ipmi: Don't use BMC product/dev ids in the BMC name")
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Message-Id: <20191021200649.1511-1-navid.emamdoost@gmail.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>