sizes.h: Add SZ_1T macro

Today drivers/pci/controller/pci-xgene.c defines SZ_1T

Move it into linux/sizes.h so that it can be re-used elsewhere.

Link: https://lore.kernel.org/r/575cb7164cf124c75df7cb9242ea7374733942bf.1642752946.git.christophe.leroy@csgroup.eu


Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Krzysztof Wilczyński <kw@linux.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Toan Le <toan@os.amperecomputing.com>
Cc: linux-pci@vger.kernel.org