The man page says it:
Note: there are no ciphersuites specific to TLS v1.1.
TLS 1.1 uses the same cipher suites as TLS 1.0, therefore OpenSSL does not make a distinction between the two. When it supports a cipher suite for TLS 1.1, it also supports it for TLS 1.0, and vice versa.
TLS 1.2 has its own set of cipher suites because these include the definition of the underlying hash function for the "PRF". The PRF is an internal construction in TLS, which is used to derive the master secret into actual encryption and MAC keys, and similar usages. In SSL 3.0, TLS 1.0 and TLS 1.1, the PRF uses a combination of MD5 and SHA-1; in TLS 1.2, the PRF relies on a specific hash function which depends on the cipher suite.
TLS 1.2 also adds support for cipher suites with authenticated encryption, i.e. GCM. These do not work with previous TLS versions.