target/arm: Add new 's1_is_el0' argument to get_phys_addr_lpae()

target/arm: Add new 's1_is_el0' argument to get_phys_addr_lpae()

For ARMv8.2-TTS2UXN, the stage 2 page table walk wants to know
whether the stage 1 access is for EL0 or not, because whether
exec permission is given can depend on whether this is an EL0
or EL1 access. Add a new argument to get_phys_addr_lpae() so
the call sites can pass this information in.

Since get_phys_addr_lpae() doesn't already have a doc comment,
add one so we have a place to put the documentation of the
semantics of the new s1_is_el0 argument.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200330210400.11724-4-peter.maydell@linaro.org