arm64: Add brackets around user_stack_pointer()

arm64: Add brackets around user_stack_pointer()

commit 2520d039728b2a3c5ae7f79fe2a0e9d182855b12 upstream.

Commit 5f888a1d33 (ARM64: perf: support dwarf unwinding in compat mode)
changes user_stack_pointer() to return the compat SP for 32-bit tasks
but without brackets around the whole definition, with possible issues
on the call sites (noticed with a subsequent fix for KSTK_ESP).

Fixes: 5f888a1d33c4 (ARM64: perf: support dwarf unwinding in compat mode)
Reported-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>