msm_serial_hs: Fix type inconsistency for tx and rx command_ptr_ptr
Both tx and rx command_ptr_ptr are of type u32*. While allocating
memory for it, sizeof(u32 *) is used as part of kmalloc API instead
of sizeof(u32). ADM Hardare requires size of command_ptr_ptr as 1 Word.
Both sizeof(u32 *) and sizeof(u32) are same on 32-bit architecture
whereas sizeof(u32 *) would be different in size compare to sizeof(u32)
on anyother architecture.
Hence correct usage of sizeof(command_ptr_ptr) for Tx and Rx with
kmalloc and dma_(map/unmap)_single APIs.