[X86][MC] Fix parsing Intel syntax indirect branch with symbol only

Clang on Windows targets often requires indirect calls through the
import address table (IAT), and also .refptr stubs for MinGW target.
On 32-bit this generates assembly in the form of
`call dword ptr [__imp__func]`, which MC had failed to handle correctly.
64-bit targets are not affected because rip-relative addressing is used.

Reported on: https://github.com/llvm/llvm-project/issues/62010

Depends on D149695, D149920

Differential Revision: https://reviews.llvm.org/D149579