Add missing u8 eos[2] declaration to struct smbios_type38

Each smbios entry should be followed with two null bytes. In other
structures it's done by adding `u8 eos[2]` extra bytes at the end, it
was omitted in type38 (IPMI) though. This change fixes this - tables
decodes nicely:

```
IPMI Device Information
        Interface Type: KCS (Keyboard Control Style)
        Specification Version: 2.0
        I2C Slave Address: 0x10
        NV Storage Device: Not Present
        Base Address: 0x0000000000000CA2 (I/O)
        Register Spacing: 32-bit Boundaries
```

Signed-off-by: Lukasz Siudut <lsiudut@fb.com>
Change-Id: I8efea9612448f48e23e7b2226aea2a9f3bc21824
Reviewed-on: https://review.coreboot.org/c/31482
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/smbios.h

@@ -493,6 +493,7 @@ struct smbios_type38 {
 	u64 base_address;
 	u8 base_address_modifier;
 	u8 irq;
+	u8 eos[2];
 } __packed;
 
 enum smbios_bmc_interface_type {