UPSTREAM: kasan, arm64: remove redundant ARCH_SLAB_MINALIGN define

(Upstream commit 7fa1e2e6afa7f4c9f46528e61de6a15d9e8dffd9).

Defining ARCH_SLAB_MINALIGN in arch/arm64/include/asm/cache.h when KASAN
is off is not needed, as it is defined in defined in include/linux/slab.h
as ifndef.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Bug: 128674696
Change-Id: I27d13c0ed9f8ab2488028b526561f90b3e2eec0c