GPRS HTTP 400 Bad request
I solved the problem. :)
The problem was with Extra "Space" in header.

sprintf(DataToSend, "GET %s HTTP/1.1\r\n Host: %s\r\n\r\n", PATH, HOST);


I removed that space:

sprintf(DataToSend, "GET %s HTTP/1.1\r\nHost: %s\r\n\r\n", PATH, HOST);


and then problem get resolved. 
here is the response from server:

HTTP/1.1 200 OK
Date: Fri, 19 Jun 2015 03:38:14 GMT
Server: Apache
X-Powered-By: PHP/5.4.34
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Last-Modified: Fri, 19 Jun 2015 03:38:14 GMT
Vary: Accept-Encoding,User-Agent
Content-Length: 87
Content-Type: text/plain

This is REQUEST Data
data1:value1
This is GET Data
data1:value1
This is POS
           HTTP/1.1 200 OK
Date: Fri, 19 Jun 2015 03:38:14 GMT
Server: Apache
X-Powered-By: PHP/5.4.34
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Last-Modified: Fri, 19 Jun 2015 03:38:14 GMT
Vary: Accept-Encoding,User-Agent
Content-Length: 87
Content-Type: text/plain

This is REQUEST Data
data1:value1
This is GET Data
data1:value1
This is POS
           T Data


Thanks guys.