UC_ERR_ARG when attempting to write to c1_c0_2 arm register

[wr3nchsr]

Describe the bug
The c1_c0_2 register in arm raises an Invalid argument (UC_ERR_ARG) error when writing to it.
This was tested with qiling version 1.4.6 and unicorn version 2.1.1

Sample Code
Run the example hello_arm_linux_debug.py or the following code:

ql = Qiling(code=bytes(1000), archtype=QL_ARCH.ARM, ostype=QL_OS.LINUX)

This will call the enable_vfp function from QlArchARM which will attempt to write to c1_c0_2 and raise the error.

Screenshots

Additional context
This is caused because of this unicorn commit which changed the default return value of reg_write function from UC_ERR_OK to UC_ERR_ARG.

Furthermore, the switch case handling register UC_ARM_REG_C1_C0_2 in the reg_write function is commented out as shown here which causes the function to return the default return value.

and the register UC_ARM_REG_C1_C0_2 is commented as depreciated and should be replaced with UC_ARM_REG_CP_REG here.

[elicn]

Unicorn upgrade to version 2.1.1 broke Qiling which has not adapted yet, however that is to be resolved soon. Currently there are three options to work around this:

1. Wait for Qiling to catch up with latest Unicorn changes
2. Apply pending changes in Qiling (Adjust Qiling to comply with latest changed in Unicorn 2.1.2 #1499) and adjust your code accordingly. That is, using the newly introduced methods ql.arch.cpr.read and ql.arch.cpr.write (see commit 3c5ff2d for examples of how to use it)
3. Revert Unicorn to version 2.0.1