armv7: psci: make v7_flush_dcache_all public for all psci code

armv7: psci: make v7_flush_dcache_all public for all psci code

The v7_flush_dcache_all function will be called by ls102xa platform system
suspend, it is necessary to make it a public call instead of a local one, but
changing the LENTRY to ENTRY isn't enough, because there is another one using
the same name, so this one gets a psci_ prefix.

Signed-off-by: Hongbo Zhang <[email protected]>
Reviewed-by: Tom Rini <[email protected]>
Reviewed-by: York Sun <[email protected]>