Panic occurs when an ID is requested from an exhausted resource pool

Panic occurs when an ID is requested from a resource pool that does not have any free ID.

Stack trace:
panic: runtime error: index out of range [4] with length 4
goroutine 32236 [running]:
github.com/boljen/go-bitmap.Set(...)
/go/src/vendor/github.com/boljen/go-bitmap/bitmap.go:47
github.com/boljen/go-bitmap.Bitmap.Set(...)
/go/src/vendor/github.com/boljen/go-bitmap/bitmap.go:104
github.com/boljen/go-bitmap.Threadsafe.Set(0xc003cba298, 0x4, 0x6, 0x0, 0x0, 0x0, 0x20, 0x414501)
/go/src/vendor/github.com/boljen/go-bitmap/bitmap.go:162 +0x185
github.com/opencord/voltha-lib-go/v5/pkg/ponresourcemanager.(*PONResourceManager).GenerateNextID(0xc00051c0b0, 0x12e19e0, 0xc00ba24b40, 0xc00b4e30b0, 0x36, 0xc00b4e30b0, 0x0)
/go/src/vendor/github.com/opencord/voltha-lib-go/v5/pkg/ponresourcemanager/ponresourcemanager.go:1337 +0x246
github.com/opencord/voltha-lib-go/v5/pkg/ponresourcemanager.(*PONResourceManager).GetResourceID(0xc00051c0b0, 0x12e19e0, 0xc00ba24b40, 0x1, 0x117c167, 0x6, 0xc000000001, 0x203001, 0xc006e987b0, 0x24, ...)
/go/src/vendor/github.com/opencord/voltha-lib-go/v5/pkg/ponresourcemanager/ponresourcemanager.go:812 +0x7a5
github.com/opencord/voltha-openolt-adapter/internal/pkg/resourcemanager.(*OpenOltResourceMgr).GetONUID(0xc0004de3c0, 0x12e19e0, 0xc00ba24b40, 0x1, 0x10, 0xc00b4e2ea0, 0x0)
/go/src/internal/pkg/resourcemanager/resourcemanager.go:401 +0x89
github.com/opencord/voltha-openolt-adapter/internal/pkg/core.(*DeviceHandler).onuDiscIndication(0xc00022c000, 0x12e19e0, 0xc00ba24b40, 0xc00ba24a50, 0x12, 0xc009884750)
/go/src/internal/pkg/core/device_handler.go:1367 +0x1b4e
github.com/opencord/voltha-openolt-adapter/internal/pkg/core.(*DeviceHandler).onuIndicationsRoutine(0xc00022c000, 0xc00545d7f0, 0x2)
/go/src/internal/pkg/core/device_handler.go:2803 +0x316
created by github.com/opencord/voltha-openolt-adapter/internal/pkg/core.(*DeviceHandler).getOnuIndicationChannel
/go/src/internal/pkg/core/device_handler.go:2763 +0x1eb