x86 I/O APIC: Make functions `io_apic_{read,write}()` public

Some LPC initialiation can save some lines of code when being able
to use the functions `io_apic_read()` and `io_apic_write()`.

As these two functions are now public, remove them from the generic
driver as otherwise we get a build errors like the following.

    Building roda/rk9; i386: ok, using i386-elf-gcc
    Using payload /srv/jenkins/payloads/seabios/bios.bin.elf
      Creating config file... (blobs, ccache) ok;  Compiling image on 4 cpus in parallel .. FAILED after 12s!
    Log excerpt:
    coreboot-builds/roda_rk9/arch/x86/lib/ramstage.o: In function `io_apic_write':
    /srv/jenkins/.jenkins/jobs/coreboot-gerrit/workspace/src/arch/x86/lib/ioapic.c:32: multiple definition of `io_apic_write'
    coreboot-builds/roda_rk9/drivers/generic/ioapic/ramstage.o:/srv/jenkins/.jenkins/jobs/coreboot-gerrit/workspace/src/drivers/generic/ioapic/ioapic.c:22: first defined here
    collect2: error: ld returned 1 exit status
    make: *** [coreboot-builds/roda_rk9/generated/coreboot_ram.o] Error 1
    make: *** Waiting for unfinished jobs....

Change-Id: Id600007573ff011576967339cc66e6c883a2ed5a
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/3180
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>
3 files changed