x86/sev: Fix calculation of end address based on number of pages

When calculating an end address based on an unsigned int number of pages,
any value greater than or equal to 0x100000 that is shift PAGE_SHIFT bits
results in a 0 value, resulting in an invalid end address. Change the
number of pages variable in various routines from an unsigned int to an
unsigned long to calculate the end address correctly.

Fixes: 5e5ccff6 ("x86/sev: Add helper for validating pages in early enc attribute changes")
Fixes: dc3f3d24

 ("x86/mm: Validate memory when changing the C-bit")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/6a6e4eea0e1414402bac747744984fa4e9c01bb6.1686063086.git.thomas.lendacky@amd.com