aarch64: ABI: Remove slim_* APIs from whitelist

As the slim_* APIs are exported via a module that's enabled
in lahaina_GKI.config, they need not be whitelisted. Hence,
exclude them from the whitelist.

Change-Id: Idc10bed503b987710558d8bed32ab340afcef81d
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>