LinuxKPI: acpi: fix guid_t argument type

acpi_check_dsm() and acpi_evaluate_dsm_typed() take a guid_t argument
and not a char *. For in-tree Linux based drivers this leads to a
compile error due to a warning. Fix the function argument type and
cast internally.

While this made the long statements in the wrapper functions for *_dsm_*
even less readable split them up using a local variable.

Sponsored by: The FreeBSD Foundation
MFC after: 3 days
Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D51649