Staging: heci: fix setting h_is bit in h_csr register

Staging: heci: fix setting h_is bit in h_csr register

Host software could issue interrupts to ME firmware, using H_IG bit. While
Setting H_IG bit, host software should preserve all the other bits in H_CSR
unchanged. In the original function which sets H_CSR register, they first read
the register, then set some bits, and write the whole 32bits back to the
register. And that the special behavior of H_IS (write-one-to-zero) causes problem.
This patch fixes the issue in the following ways:

 - Modify heci_set_csr_register() function so that it doesn't change H_IS bit.
 - Add interface heci_csr_clear_his() to clear H_IS bit. This function is called
   after H_IS checking (dev->host_hw_state & H_IS == H_IS).
 - In original heci_csr_disable_interrupts() function, it not only clears H_IE
   bit, sometimes it also clears H_IS bit. This patch separates the two parts.
 - Avoid calling write_heci_register() function to set H_CSR register directly,
   and instead using heci_set_csr_register() function

Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>