Revert "percpu: include irqflags.h for raw_local_irq_save()"

This reverts commit 0d796a9e6a93608b4dd84fbd09f01e912ae34bdc.

After merging stable release 4.19.266 into the -rt branch, an x86
build will fail with the following error:

    .../include/linux/percpu-defs.h:49:34: error: 'PER_CPU_BASE_SECTION' undeclared here (not in a function); did you mean 'PER_CPU_FIRST_SECTION'?

This is due to an #include loop:

    <asm/percpu.h>
     -> <linux/irqflags.h>
         -> <asm/irqflags.h>
             -> <asm/nospec-branch.h>
                 -> <asm/percpu.h>

which appears after the merge because:

- The reverted commit added <asm/percpu.h> -> <linux/irqflags.h>
- 4.19.266 added <asm/nospec-branch.h> -> <asm/percpu.h>

Neither upstream nor any other maintained stable-rt branch has this
include, and my build succeeded without it.  Revert it here as well.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Link: https://lore.kernel.org/r/Y5O/aVw/zHKqmpu7@decadent.org.uk
Signed-off-by: Daniel Wagner <wagi@monom.org>
1 file changed