x86/MCE/AMD: Fix mce_severity_amd_smca() signature

Change the err_ctx type to "enum context" to match the type passed in.

No functionality change.

Suggested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/20171106174633.13576-2-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>