Fix EFR32 lighting-app RPC build (#5820)
Fix EFR32 lighting-app RPC build (#5820)

Currently boots with hardfault:
   Failed do a malloc on HEAP. Is it too small ?

Statically allocate the memory for the RPC task.
project-chip/connectedhomeip,project-chip/connectedhomeip,project-chip/connectedhomeip,nestlabs/connectedhomeip,project-chip/connectedhomeip,nestlabs/connectedhomeip,nestlabs/connectedhomeip,project-chip/connectedhomeip,nestlabs/connectedhomeip,project-chip/connectedhomeip,nestlabs/connectedhomeip,nestlabs/connectedhomeip,nestlabs/connectedhomeip