Update arm pack manager for GR-PEACH
Update arm pack manager for GR-PEACH

I changed the information("sectors" and "memory") of GR-PEACH for supporting bootloader in index.json file of arm pack manager.

betzw/mbed-os,betzw/mbed-os,kjbracey-arm/mbed,kjbracey-arm/mbed,andcor02/mbed-os,kjbracey-arm/mbed,mbedmicro/mbed,mbedmicro/mbed,c1728p9/mbed-os,andcor02/mbed-os,mbedmicro/mbed,andcor02/mbed-os,mbedmicro/mbed,andcor02/mbed-os,c1728p9/mbed-os,kjbracey-arm/mbed,mbedmicro/mbed,andcor02/mbed-os,c1728p9/mbed-os,betzw/mbed-os,c1728p9/mbed-os,c1728p9/mbed-os,betzw/mbed-os,andcor02/mbed-os,betzw/mbed-os,betzw/mbed-os,c1728p9/mbed-os