powerpc/32/booke: Fix the build error when CRASH_DUMP is enabled

In the current code, the RELOCATABLE will be forcedly enabled when
enabling CRASH_DUMP. But for ppc32, the RELOCABLE also depend on
ADVANCED_OPTIONS and select NONSTATIC_KERNEL. This will cause the
following build error when CRASH_DUMP=y && ADVANCED_OPTIONS=n because
the select of NONSTATIC_KERNEL doesn't take effect.

  arch/powerpc/include/asm/io.h: In function 'virt_to_phys':
  arch/powerpc/include/asm/page.h:113:26: error: 'virt_phys_offset' undeclared (first use in this function)
   #define VIRT_PHYS_OFFSET virt_phys_offset
                          ^
It doesn't have any strong reasons to make the RELOCATABLE depend on
ADVANCED_OPTIONS. So remove this dependency to fix this issue.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>