ipmi_si: fix a memleak in try_smi_init()

In the Linux kernel, the following vulnerability has been resolved:

ipmi_si: fix a memleak in try_smi_init()

Kmemleak reported the following leak info in try_smi_init():

unreferenced object 0xffff00018ecf9400 (size 1024):

comm "modprobe", pid 2707763, jiffies 4300851415 (age 773.308s)

backtrace:

[<000000004ca5b312>] __kmalloc+0x4b8/0x7b0

[<00000000953b1072>] try_smi_init+0x148/0x5dc [ipmi_si]

[<000000006460d325>] 0xffff800081b10148

[<0000000039206ea5>] do_one_initcall+0x64/0x2a4

[<00000000601399ce>] do_init_module+0x50/0x300

[<000000003c12ba3c>] load_module+0x7a8/0x9e0

[<00000000c246fffe>] __se_sys_init_module+0x104/0x180

[<00000000eea99093>] __arm64_sys_init_module+0x24/0x30

[<0000000021b1ef87>] el0_svc_common.constprop.0+0x94/0x250

[<0000000070f4f8b7>] do_el0_svc+0x48/0xe0

[<000000005a05337f>] el0_svc+0x24/0x3c

[<000000005eb248d6>] el0_sync_handler+0x160/0x164

[<0000000030a59039>] el0_sync+0x160/0x180

The problem was that when an error occurred before handlers registration

and after allocating `new_smi->si_sm`, the variable wouldn't be freed in

the error handling afterwards since `shutdown_smi()` hadn't been

registered yet. Fix it by adding a `kfree()` in the error handling path

in `try_smi_init()`.