selftests: mm: move fpregs printing

arm64's fpregs are not at a constant offset from sigcontext. Since this is
not an important part of the test, don't print the fpregs pointer on arm64.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20240822151113.1479789-26-joey.gouly@arm.com


Signed-off-by: Will Deacon <will@kernel.org>