fix building of otacerts.zip
fix building of otacerts.zip

Was using a variable which was only defined inside the rule, outside
the rule.  Change to use the correct variable.

RR-msm7x30/platform_manifest,fallouttester/platform_manifest,hagar006/platform_manifest,xorware/android_build,pranav01/platform_manifest,xorware/android_build,xorware/android_build,xorware/android_build,knone1/platform_manifest,ND-3500/platform_manifest,see4ri/lolili,Hybrid-Power/startsync,xorware/android_build