exec: Fix CPU rework fallout

Commit 259186a7d2f7184efc96ae99bc5658e6159f53ad (cpu: Move halted and
interrupt_request fields to CPUState) passed CPUState::env_ptr to
tlb_flush() directory rather than through a typed variable.

Commit 00c8cb0a36f51a6866a83c08962d12a0eb21864b (cputlb: Change
tlb_flush() argument to CPUState) now changed the argument type.
This was unnoticed by gcc because env_ptr is a void pointer.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>