arm32: kaslr: Fix the bitmap error

Offering: HULK
hulk inclusion
category: bugfix
bugzilla: 172972 https://gitee.com/openeuler/kernel/issues/I4DDEL



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The value returned by get_region_number may exceed the
usable memory positions indexed by bitmap, it will cause
probabilistic boot failure in images which enabled kaslr.

Fixes: 156b9ca54d0d ("[Backport] ARM: decompressor: add KASLR support")
Signed-off-by: Cui GaoSheng <cuigaosheng1@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>