This patch fixes booting when idmap pgd lays above 4gb. Commit
4756dcbf mostly had fixed this, but it'd failed to load upper bits.

Also this fixes adding TTBR1_OFFSET to TTRR1: if lower part overflows
carry flag must be added to the upper part.
Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>