CTR mode: Kconfig cyclic dependency

[Stephan Mueller <smueller@chronox.de>]

Hi Herbert,

during the finalization of my patch set for converting the CTR DRBG over to 
CTR AES, I ran into a Kconfig problem. Maybe you have an idea how to resolve 
it.

As the CTR DRBG now uses the CTR mode, I added "select CRYPTO_CTR" to 
CRYPTO_DRBG_CTR. This now lead to the following cyclic dependency:

crypto/Kconfig:1547:error: recursive dependency detected!
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
crypto/Kconfig:1547:    symbol CRYPTO_DRBG_MENU is selected by 
CRYPTO_RNG_DEFAULT
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
crypto/Kconfig:83:      symbol CRYPTO_RNG_DEFAULT is selected by CRYPTO_SEQIV
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
crypto/Kconfig:255:     symbol CRYPTO_SEQIV is selected by CRYPTO_CTR
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
crypto/Kconfig:286:     symbol CRYPTO_CTR is selected by CRYPTO_DRBG_CTR
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
crypto/Kconfig:1566:    symbol CRYPTO_DRBG_CTR depends on CRYPTO_DRBG_MENU

i.e. CRYPTO_RNG_DEFAULT -> CRYPTO_DRBG_MENU -> CRYPTO_CTR -> CRYPTO_SEQIV -> 
CRYPTO_RNG_DEFAULT

Thanks
Stephan