[Trivial] emberAfIsTypeSigned doesn't return true for all signed types

[hasty]

Type

Other

Explanation

Namely, ZCL_POWER_MW_ATTRIBUTE_TYPE, ZCL_AMPERAGE_MA_ATTRIBUTE_TYPE, ZCL_VOLTAGE_MV_ATTRIBUTE_TYPE, ZCL_ENERGY_MWH_ATTRIBUTE_TYPE

Platform

all

Platform Version(s)

No response

Testing

Manually tested with SDK

(Optional) If manually tested please explain why this is only manually tested

No response

Anything else?

No response

[bzbarsky-apple]

Note that this will become IsSignedIntegerAttribute in https://github.com/project-chip/connectedhomeip/pull/32632