proc: Use underscores for SSBD in 'status'

proc: Use underscores for SSBD in 'status'

The style for the 'status' file is CamelCase or this. _.

Fixes: fae1fa0fc ("proc: Provide details on speculation flaw mitigations")
OraBug: 28041771
CVE: CVE-2018-3639

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
(cherry picked from commit e96f46ee8587607a828f783daa6eb5b44d25004d)
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Mihai Carabas <mihai.carabas@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>