Revert "[IMM32] ImmInstallIMEW: Use uppercase filename" (reactos#8767)

Reverts reactos#8763.
We should consider case-sensitive
file-systems we have.

Author: katahiromz

win32ss/user/imm32/install.c

@@ -514,7 +514,6 @@ ImmInstallIMEW(
     WCHAR szImeFileName[MAX_PATH];
     PWSTR pchFileTitle;
     GetFullPathNameW(lpszIMEFileName, _countof(szImeFileName), szImeFileName, &pchFileTitle);
-    CharUpperW(szImeFileName);
     if (IS_NULL_UNEXPECTEDLY(pchFileTitle))
         return NULL;