desktop: update: Add support for mips64.

Change-Id: I48c6d717e30491171936e34210e8c60b1c7f9487
Reviewed-on: https://gerrit.libreoffice.org/16909Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

desktop/test/deployment/update/platform/readme.txt

@@ -7,7 +7,9 @@ linux_arm_eabi.oxt: linux_arm_eabi
 linux_arm_oabi.oxt: linux_arm_oabi
 linux_ia64.oxt: linux_ia64
 linux_mips_eb.oxt: linux_mips_eb
+linux_mips64_eb.oxt: linux_mips64_eb
 linux_mips_el.oxt: linux_mips_el
+linux_mips64_el.oxt: linux_mips64_el
 linux_powerpc64.oxt: linux_powerpc64
 linux_powerpc.oxt: linux_powerpc
 linux_s390.oxt: linux_s390