ANDROID: KVM: arm64: Fix build issue without CONFIG_ARM64_LSE_ATOMICS

__LSE_PREAMBLE is only defined with CONFIG_ARM64_LSE_ATOMICS, which
defaults to CONFIG_ARM64_USE_LSE_ATOMICS, without it the build fails.

__lse_ll_sc_body is already aware of CONFIG_ARM64_LSE_ATOMICS and
doesn't use __lse_* if not enabled, so just guard the definition of
the function.

Bug: 278749606

Change-Id: I9e2bed920585f79c11ca26e29d2ea748931ca2b9
Signed-off-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Will Deacon <willdeacon@google.com>