Kconfig: memtest: update number of test patterns up to 17

Kconfig: memtest: update number of test patterns up to 17

Additional test patterns for memtest were introduced since commit
63823126c221 ("x86: memtest: add additional (regular) test patterns"),
but looks like Kconfig was not updated that time.

Update Kconfig entry with the actual number of maximum test patterns.

Signed-off-by: Vladimir Murzin <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Russell King <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>