ARM: keystone: fix integer overflow warning

stable inclusion
from stable-5.10.32
commit 505c48942f04072f7b005c30d35ebf149f50afd7
bugzilla: 51796

--------------------------------

[ Upstream commit 844b85dd ]

clang warns about an impossible condition when building with 32-bit
phys_addr_t:

arch/arm/mach-keystone/keystone.c:79:16: error: result of comparison of constant 51539607551 with expression of type 'phys_addr_t' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
            mem_end   > KEYSTONE_HIGH_PHYS_END) {
            ~~~~~~~   ^ ~~~~~~~~~~~~~~~~~~~~~~
arch/arm/mach-keystone/keystone.c:78:16: error: result of comparison of constant 34359738368 with expression of type 'phys_addr_t' (aka 'unsigned int') is always true [-Werror,-Wtautological-constant-out-of-range-compare]
        if (mem_start < KEYSTONE_HIGH_PHYS_START ||
            ~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~

Change the temporary variable to a fixed-size u64 to avoid the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Link: https://lore.kernel.org/r/20210323131814.2751750-1-arnd@kernel.org

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Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>