Move the check on multisim support when switch configuration is done

The methods switchMultiSimConfig() and isMultisimSupported() in
TelephonyManager have different permissions. So, in order to check if
the switch operation can be performed, the check needs to be moved after
the verification of the permissions.

Bug: 124462964
Test: compilation
Change-Id: I501110d8b3fb2d26e4dfe187b52bb45dc8b5dc4b