driver: host-subs: replace defined() macro with IS_ENABLED().

Replace marco function, defined(), with IS_ENABLED() in host sub-devices
driver implementation. In this PR, we won't replace the macros which
cause -Wimplicit-function-declaration warning if related configuration
is not enabled or its type is not boolean..

Signed-off-by: Mulin Chao <mlchao@nuvoton.com>