linux-user: Pass CPUArchState to target_restore_altstack

linux-user: Pass CPUArchState to target_restore_altstack

In most cases we were already passing get_sp_from_cpustate
directly to the function.  In other cases, we were passing
a local variable which already contained the same value.
In the rest of the cases, we were passing the stack pointer
out of env directly.

Reviewed by: Warner Losh <[email protected]>
Signed-off-by: Richard Henderson <[email protected]>
Message-Id: <20210426025334.1168495[email protected]>
Signed-off-by: Laurent Vivier <[email protected]>