KVM: arm64: Fix compilation when CONFIG_ARM64_USE_LSE_ATOMICS=n
__lse_swap_desc() is compiled unconditionally, even if LSE is disabled
using the config option. Align with the spirit of the config option and
fix some build errors due to __LSE_PREAMBLE being undefined with the
application of some ifdeffery.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511250700.kAutzJFm-lkp@intel.com/
Link: https://msgid.link/20251124235409.1731253-1-oupton@kernel.org
Signed-off-by: Oliver Upton <oupton@kernel.org>