sparc/mm: export symbols for lazy_mmu_mode KUnit tests

sparc/mm: export symbols for lazy_mmu_mode KUnit tests

The lazy_mmu_mode KUnit tests call lazy_mmu_mode_{enable,disable}.  These
tests may be built as a module, and because of inlining this means that
arch_{enter,flush,leave}_lazy_mmu_mode need to be exported.

[akpm@linux-foundation.org: remove mm/tests/lazy_mmu_mode_kunit.c comment, per Kevin]
Link: https://lkml.kernel.org/r/20251218100541.2667405-1-kevin.brodsky@arm.com
Fixes: ee628d9cc8d5 ("mm: add basic tests for lazy_mmu")
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>