ACPI: GED: fix -Wformat

Clang is more aggressive about -Wformat warnings when the format flag
specifies a type smaller than the parameter. It turns out that gsi is an
int. Fixes:

drivers/acpi/evged.c:105:48: warning: format specifies type 'unsigned
char' but the argument has type 'unsigned int' [-Wformat]
trigger == ACPI_EDGE_SENSITIVE ? 'E' : 'L', gsi);
                                            ^~~

Link: https://github.com/ClangBuiltLinux/linux/issues/378
Fixes: ea6f3af4

 ("ACPI: GED: add support for _Exx / _Lxx handler methods")
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>