arm64: ssbd: Drop #ifdefs for PR_SPEC_STORE_BYPASS

Now that we're all merged nicely into mainline, there's no need to check
to see if PR_SPEC_STORE_BYPASS is defined.

Change-Id: I2a29294b23482358823f4efd9b2a6b2360c242bc
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-commit: 2d1b2a91d56b19636b740ea70c8399d1df249f20
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>